Labor Day featured memorable matches at the 2016 US Open. Karolina Pliskova outlasted Venus Williams, advancing to the Quarterfinals in a 3rd-set tie-break. 18-year-old Ana Konjuh avenged her loss at Wimbledon, defeating World #4 Agnieszka Radwanska in straight-sets. Serena Williams and Andy Murray dominated with clinical performances over Yaroslava Svedova and Grigor Dimitrov. Meanwhile, Juan Martin Del Potro will carry some extra rest in the Quarters after Dominic Thiem retired from their Round of 16 match. Over on Armstrong, 2014 Finalist Kei Nishikori actually out-served Ivo Karlovic to reach the Quarters, while Stan Wawrinka and Simona Halep also booked their tickets to the Final-Eight.
Juan Martin Del Potro (ARG) def  Dominic Thiem (AUT)
Final 6-3, 3-2 RET. World #10 Dominic Thiem was up a break in the 1st-set Monday morning, but Juan Martin Del Potro’s forehand didn’t seem to care. After falling behind 1-3, Delpo dominated, winning five consecutive games to take the set.
Juan jumped ahead early in the second, earning a break before the first changeover. The oft-deadly Thiem backhand was no match for Del Potro’s overpowering wrist-rocket, but Thiem’s mobility was also at issue. After an hour and 8-minutes, Domionic took an extended medical time-out, as trainers worked on his right quadriceps.
Didn’t help. Thiem won his next service game, then waved the white flag – the 9th retirement of this year’s Open. Must be an Olympic year.
With the retirement, Juan Martin Del Potro is through to his fourth US Open Quarterfinal; thrilled to be back on the stage where he won his only Grand Slam singles title in 2009, ending Roger Federer’s epic five-year US Open win-streak. Delpo after the match: “I don’t know if I’m playing better than 2009, but I keep winning…” UP NEXT: Stan Wawrinka.
Juan Martin del Potro, the beloved gentle giant https://t.co/YQW7n7Cov8
— ESPNTennis (@ESPNTennis) September 4, 2016
Juan Martin Del Potro (No.142) is aiming to become the lowest-ranked @usopen quarter-finalist since Jimmy Connors (No.174) in 1991.
— Michal Samulski (@MichalSamulski) September 5, 2016
— luciahoff (@luciahoff) September 5, 2016
 Karolina Pliskova (CZE) def  Venus Williams (USA)
Final 6-4, 4-6, 7-6(3). Last year, Venus defeated Karolina Pliskova in the inaugural WTA Elite Trophy Final, and returned to the WTA’s top-10 for the first time in 4-and-a-half years.
On Monday, she jumped out to a 3-0 lead early, then broke again to go up 5-1, serving for the set. Pliskova wasn’t done. She scored her first break, then consolidated to close the gap, 3-5. Attacking Venus’ second-serve, Karolina shot ahead 0-30 in game-9. Two big serves from Williams leveled it, but a booming return gave Pliskova another break point. High drama. Venus found deuce, took the ad, but sent a forehand long to bring it back to deuce. Pliskova earned a second break point, then Venus dropped a double fault to get us back on serve, 5-4 Williams. Pliskova, serving to stay in the set, fell behind 0-40 thanks to Venus’s overpowering ground-strokes. At 30-40, second-serve, Venus pounced again and earned set-1 with a break.
In the second, Venus earned an early break again. Pliskova answered with a break of her own. After 63-minutes, we were all-even at 3-games a piece. Karolina broke again, earning her first lead of the match 4-3. She consolidated to win her fourth consecutive game, then leveled the match on her next service game, taking set-2, 6-4.
In the third, Pliskova dialed her first-serve up to 11. Venus struggled. Williams fought through deuce in most of her service games, while Karolina cruised through service wins. At the first changeover, the Cincinnati champ was up a break. In game-4, Karolina erased three break points to maintain the edge. She simply needed to hold the rest of the way to reach her first Grand Slam Quarterfinal.
Venus’ serve resurfaced. She got it to 3-4, then broke to level the decider. We were at 4-all with momentum clearly behind the 2-time US Open champ. Venus would hold another tight deuce battle to regain the lead, forcing Pliskova to serve just to stay in the match. Pressure.
Down 30-40, Pliskova erased match-point with a half-volley, rocketed an unreachable forehand for the advantage, and scored a clutch win to keep the match alive.
At 5-all, it was Karolina’s turn to make Venus sweat. At 30-40, Venus pounded a forehand past Pliskova’s backhand-wing to erase break-point – but then, sent a forehand long. Advantage Karolina. Pliskova stole the break on a net-cord; then after the sit-down, jumped ahead 40-love. Improbably, Venus erased all three match points and drilled two ridiculously clutch winners to force the tie-break.
Karolina grabbed the edge early in the tie-break and found herself up 4-2 at the change of ends. After 2-hours and 24-minutes, Pliskova won it: 4-6, 6-4, 7-6(3).
It’s been a hell of a year for Karolina Pliskova. She comes into this year’s US Open after winning her second title of the year in Cincinnati, defeating World #2 and Olympic Silver Medalist Angelique Kerber in straight sets 6-3, 6-1. UP NEXT: Ana Konjuh.
— US Open Tennis (@usopen) September 5, 2016
 Serena Williams (USA) def Yaroslava Shvedova (KAZ)
Final 6-2, 6-3. With Monday’s routine thumping of Yaroslava Shvedova, Serena Williams broke the record for the most Grand Slam match victories in the Open Era. With her 308th Major win, she surpasses Roger Federer, just two days after surpassing Martina Navratilova’s record of 307 Major wins. She hasn’t lost-serve throughout the tournament, and has only faced one break point – from Johanna Larsson in Round-3. With the victory, she’s reached her 9th consecutive and 14th-career US Open Quarterfinal. UP NEXT: Simona Halep.
Serena Williams now has the most major match wins in the Open Era passing Roger Federer. pic.twitter.com/8JPDkQ7uC9
— SportsCenter (@SportsCenter) September 5, 2016
 Andy Murray (GBR) def  Grigor Dimitrov (BUL)
Final 6-1, 6-2, 6-2. Back in March, Grigor Dimitrov defeated the Andy Murray in Miami’s 3rd-Round, after losing the first-set in a tie-break. Tonight, in the US Open Round of 16, he simply struggled to put games on the board.
But let’s be honest, since March, the World #2 has been on a tear. During the clay swing, Andy reached the Semi’s in Monte Carlo, the Final in Madrid, won the title in Rome, then fell to Djokovic in the French Open Final. After Roland Garros, he won 22 consecutive matches, winning Queens Club, Wimbledon and Olympic Gold. Insane. Murray then reached his 19th career Masters-1000 Final in Cincinnati before heading to Flushing Meadows. Clearly, he has his eye on becoming the first player from Great Britain to become World #1 since modern rankings began in 1973. We’ll see what Novak Djokovic has to say about that over the next three months. UP NEXT: Kei Nishikori.
— BBC Tennis (@bbctennis) September 6, 2016
Andy Murray slept 12 hours last night, which apparently never happens.
Then, he played one of the matches of his life. Coincidence?
— BBC Tennis (@bbctennis) September 6, 2016
Murray Marches On
— ESPNTennis (@ESPNTennis) September 6, 2016
That was Andy Murray's joint-best win over a top-30 player in best of five. Also dropped five games vs No 11 Melzer at 2011 Aussie Open.
— Stuart Fraser (@stu_fraser) September 6, 2016
Ana Konjuh (CRO) def  Agnieszka Radwanska (POL)
Final 6-4, 6-4. (9-7) in the decider at Wimbledon. Nuts. That’s a drama-packed 2nd-Round match for a Major. In their only previous clash; back in June, Radwanska squeeked-out a win over the 18-year-old Croatian by the thinnest of margins at the All England Club. On a late night, Labor Day, Round of 16 match in Flushing, Konjuh knew she had to take risks and turn-up the heat early to slip past the Ninja. She earned the first break, served out the set, and found herself one set away from redemption.
In the second, Konjuh continued pounding pace deep, rifling rockets well out of Radwanska’s reach. Aces. Forehands. Backhands. She swung freely; power her prime tactic. Sure, there were loads of unforced errors, but these are the risks one takes against a top-5 opponent. Those riskes paid off at 4-all. Up triple break-point, Konjuh pounded a half-volley past the World #4, giving herself a chance to serve for the match. At an hour and 19-minutes…Game. Set. Match. Truly remarkable win for the 18-year-old. UP NEXT: Karolina Pliskova.
— US Open Tennis (@usopen) September 6, 2016
Unbelievable performance from 18yo Ana Konjuh, who avenges her heartbreaking Wimbledon loss to beat Radwanska. pic.twitter.com/cctQFS8qMV
— WTA Insider (@WTA_insider) September 6, 2016
Konjuh scores the biggest win of her career (d No.4 Radwanska 6-4 6-4) and with it, a spot in her 1st Major QF. pic.twitter.com/H9novpBNFc
— ESPNTennis (@ESPNTennis) September 6, 2016
Hello, Ana Konjuh! Bold tennis from the 18 year old! And the 1/4s are set. Last teen to win @usopen was '06 Sharapova.
— Chris McKendry (@ChrisMcKendry) September 6, 2016
DAY-8 UPSETS AND INTRIGUING RESULTS
-  Kei Nishikori (JPN) def  Ivo Karlovic (CRO) 6-3, 6-4, 7-6(4). The fact is, if it’s an Ivo Karlovic match, most discussions regarding serve center on the Croatian. I know it sounds crazy, but the 5’10” Nishikori completely outserved the 6’11” Karlovic on Labor Day. Impressive stuff from the 2014 US Open Finalist
-  Barbora Krejcikova / Katerina Siniakova (CZE) def  Andrea Hlavackova / Lucie Hradecka (CZE) 7-5, 7-5. Whoa! Huge result for the younger Czechs. Hlavackova and Hradecka won the title here 3-years-ago, after a Finals appearance in 2012.