NEW YORK -- The five-set jinx has been broken. Roger Federer fans can finally breathe easier after his straight-sets victory against No. 31 seed Feliciano Lopez on Saturday. He undoubtedly will go into Week 2 (and Round 4) of the US Open feeling more confident than he felt earlier in the tournament.
Federer, the 19-time Grand Slam champion, will have to defeat No. 33 seed Philipp Kohlschreiber on Monday to book a berth in his third Grand Slam quarterfinal of the year. Federer skipped the French Open, so that would make him 3-for-3 in major quarterfinals in 2017.
Kohlschreiber has had a quiet run in the tournament and has yet to play a seeded opponent, but he hasn't dropped a set. However, he's lost all 11 of his previous matches against Federer, winning just three sets.
Here's what else to watch in New York on Labor Day:
Tough Dog
Top-seeded Rafael Nadal appears to be in for a tougher fourth-round test than rival Federer. Ukrainian Alexandr Dolgopolov, ranked No. 64 in the world, stunned No. 15 seed Thomas Berdych in four sets in the second round and then lost just five games while convincingly sweeping Victor Troicki. In eight meetings, Dolgopolov, aka The Dog, has beaten Nadal twice, most recently at the Queen's Club in 2015.
Although Nadal dropped the first set in his past two matches, there's been no real indication that he won't be able to hold up his end of the bargain for a potential semifinal clash against Federer.
Exciting encounter
The Dominic Thiem-Juan Martin del Potro fourth-round match might not be at the top of most fans' watch list, but it should prove to be a fun matchup nevertheless. Both men have had dominant runs this US Open. Del Potro, the No. 24 seed, has yet to lose a set, and Thiem (No. 6) has dropped just one. Del Potro is 2-0 against Thiem, including a win at the same point in last year's US Open when the Austrian retired with a knee injury in the second set.
American women won't stay away
Three of Monday's four women's singles matches will include Americans. No. 15 seed Madison Keys will take on No. 4 Elina Svitolina of Ukraine. Keys heads into Week 2 of coming off a solid win against No. 17 Elena Vesnina.
No. 20 CoCo Vandeweghe, who roared into Round 4 by beating No. 10 Agnieszka Radwanska, will face unseeded Lucie Safarova of the Czech Republic. Vandeweghe will look to notch her third consecutive US Open quarterfinal berth (she reached the semifinals the past two years).
Jennifer Brady, the unseeded 22-year-old Pennsylvania native, runs into No. 1 Karolina Pliskova. Like the men's top seed, Pliskova is coming of two matches in which she lost the first set.
Seeing doubles
Americans Bob and Mike Bryan, five-time champions here and the fifth-seeded team in the men's doubles draw, are scheduled to take on the No. 9 pairing of Mate Pavic and Oliver Marach for a place in the quarterfinals. Hall of Famer Martina Hingis, half of the second-seeded women's doubles team with Yung-Jan Chan, will be in action against No. 13 seeds Kristina Mladenovic and Anastasia Pavlyuchenkova. The 36-year-old Hingis, the 1997 US Open singles champion, is chasing her 13th Grand Slam title in women's doubles.