MELBOURNE, Australia (AP): Serena Williams has advanced to the Australian Open quarter finals with a scrappy 7-5, 6-4 win over Barbora Strycova to open play at Rod Laver Arena yesterday. Williams is attempting to win her Open era-record 23 Grand Slam singles title, her seventh Australian Open championship and, with top-ranked Angelique Kerber’s fourth-round loss, a return to the number one ranking. She had 23 unforced errors in the first set and needed eight set points to clinch it. There were seven breaks of serve in the set, including the first four games. On the final point of the set a backhand by Williams bounced flatly on Strycova’s side of the court. The Czech player couldn’t pick it up and Williams had the first set in 55 minutes. Williams took a 4-1 lead in the second set and had her serve broken when she served for the match at 5-3. But Williams came back in the next game to break Strycova’s serve and clinch the match. Williams next plays the winner of a later match between Ekaterina Makarova and Johanna Konta. If Serena Williams needed any more incentive to win her seventh Australian Open title and a record 23rd Grand Slam major, she may have got it with top-ranked Angelique Kerber’s fourth-round loss. Williams began her match against Barbora Strycova on Rod Laver Arena yesterday knowing that if she does clinch the title next Saturday, she will overtake Kerber for the number one ranking. Williams lost the top ranking, which she had held for three consecutive years, to Kerber after the German player won the US Open in September.