US Open 2019 Day 1 round-up: Djokovic, Federer, Medvedev open with wins; Fognini, Pella and Fritz fall

Defending champion Novak Djokovic overcame a slow start to beat Spaniard Ricardo Carballes Baena in straight sets to lay down a strong marker of his title credentials.

Djokovic has also avoided a potential banana skin second-round encounter with his 2016 Wimbledon conqueror Sam Querrey, as the American was knocked out in the first-round by Cordoba winner Juan Ignacio Londero.

Cincinnati winner Daniil Medvedev opened his third campaign at the US Open with a straight-sets win over Indian Prajnesh Gunneswaran, and will next play Chile's Hugo Dellien for a place in the third round.

In the first-seeded casualty of the day, Fabio Fognini, who won his maiden Masters 1000 title at Monte Carlo earlier in the season, was shown the door by tournament debutant Reilly Opelka in a four-set clash.

Opelka knocks out Fognini in the first-round

Miomir Kecmanovic prevailed in an all-Serbian first-round match against Rio winner Laslo Djere to join compatriots Djokovic and Dusan Lajovic in the second round.

Lucky loser Paulo Lorenzi recovered from a two-set deficit to beat 16-year-old American Zachary Svajda, the youngest player in the US Open draw this year, in one of seven five-set men's singles matches on the day.

Kei Nishikori, Christian Garin, and Nikoloz Basilashvili were the other seeded winners on the day while Taylor Fritz became the second seed to fall. The young American lost to Spanish veteran Feliciano Lopez, who is making his 18th consecutive appearance at Flushing Meadows.

Lucas Pouille downed Phillip Kohlschreiber to stay on course for a potential third-round meeting with Roger Federer.

Borna Coric, the 12th seed who made the fourth round last year, opened his campaign with a straight-sets win over Russia's Evgeniy Donskoy. Meanwhile, Winston-Salem titlist Hubert Hurkacz came out second best in a five-setter against Frenchman Jeremy Chardy.

Guido Pella became the third seeded casualty on the opening day at Flushing Meadows when the Sau Paulo winner lost to Pablo Carreno Busta.

In the evening session, five-time winner Roger Federer overcame a slow start to beat Indian qualifier Sumit Nagal in four sets and book his 100th match at the tournament, against Bosnian Damir Dzumhur.