Venus Williams has advanced to the second round of the Cincinnati Open after a haphazard and lacklustre 7-6[6] 6-4 victory over Zarina Diyas.

Neither competitor could make the most of their serve in the first three games, and the veteran American saw her serve broken once again as she scraped through the tie-break.

The world number 11 then stormed into a 5-1 lead in the second set, but Diyas broke her opponent's serve twice more before Williams struggled over the line by doing the same to the Kazakh, clinching the match.

Next up for Williams is number six seed Ana Ivanovic, who received a bye in the first round.