Lleyton Hewitt and Sam Querrey kicked things off for the men's draw in Cincinnati on Sunday, winning the only two main draw matches to be played, over Jurgen Melzer and Alejandro Falla respectively. Today, the first round began in earnest - here's a roundup of the results so far.

Wimbledon doubles champion Jack Sock had his campaign ended by 16th seed Tommy Robredo in straight sets. It was a close first set, with both men serving well and no breaks of serve - Robredo eventually taking the tiebreak 7-5. Sock's serve let him down in the second, his accuracy dropping to 50% while winning just 45% of his own service points. His solitary break of Robredo's serve proved to be not nearly enough, as Sock lost his own serve three times in the second set to lose the match 7-6 6-3.

Entertaining Frenchman Gael Monfils advanced to the second round with a three set win over Feliciano Delbonis, 6-3 3-6 6-3. Monfils took two of his four break opportunities during the match and goes on to face Martin Klizan or Roberto Bautista Agut in the second round.

Spaniard Fernando Verdasco overcame compatriot Marcel Granollers in what was perhaps a more tricky match than it could have been. Both players had difficulty holding on to their serves, getting broken four times each throughout the match, the final score 5-7 6-3 7-6. Verdasco will have a difficult second round match against either Feliciano Lopez or Marin Cilic, and looks unlikely to go further.

Jerzy Janowicz, who's struggled since reaching the Wimbledon semifinals last year got his first Masters level win of the year, overcoming Teymuraz Gabashvilli 6-4 6-4. Janowicz somehow managed to avoid facing a single break point during the match, despite serving 9 double faults. He'll try to build on his win against Grigor Dimitrov in the next round - a tough task for the Pole.

Veteran German Phillip Kohlschreiber defeated Jeremy Chardy 6-3 4-6 6-4. Kohlschreiber hit nine aces during the match, and took 2 of his 8 break point opportunities. He'll face David Ferrer in round two. This was the German's first victory in three matches against Chardy.

Andy Murray's first opponent will be Joao Sousa. The Portuguese overcame Chase Buchanan in a lengthy match featuring 9 breaks of serve and two tiebreaks. The final score was 5-7 7-6 7-6, Sousa winning just one more point than Buchanan overall.

Elsewhere, there were wins for Yen-Hsun Lu over Denis Istomin, Benjamin Becker over Ivo Karlovic and for Marinko Matosevic over Nicolas Mahut - who is in danger of falling out of the top 100 after failing to replicate his excellent 2013 grass court season.

Check back tomorrow morning for a roundup of the later results from Monday's play at the Cincinnati Masters.