Melbourne, January 23:

Serena Williams willed herself to win. Sluggish early and constantly facing break points, she found just enough on Tuesday to beat 16th-seeded Shahar Peer 3-6, 6-2, 8-6 and advance to the Australian Open semi-finals, continuing her pursuit of an eighth Grand Slam title.

“I am the ultimate competitor,” said the former No 1 player, who came in unseeded after playing only four matches last year due to injury and briefly dropping out of the top 100.

Part of Williams’ competitive skills depend on how well she deals with adversity, and there was plenty against Peer, who had 13 breakpoint opportunities but was only able to convert three. Williams also shrugged off letting a 4-1 lead slip away in the deciding set. Williams next faces 17-year-old Nicole Vaidisova, who beat fellow Czech Lucie Safarova 6-1, 6-4.

On the men’s side, sixth-seeded Andy Roddick was nearly perfect in beating longtime friend and former housemate Mardy Fish 6-2, 6-2, 6-2, making only four unforced errors. He will meet top-ranked Roger Federer, who downed No 7 Tommy Robredo 6-3, 7-6 (2), 7-5.

Federer, who lost to Roddick in the finals of an exhibition tournament 10 days ago, struggled at times, losing his serve four times. But he came up with his best when he needed it, taking the last five points of the tiebreaker, then breaking Robredo as he served at 5-6 in the third. With his strong defensive skills, Robredo often made Federer hit more than one good shot to take a point, but had only 17 winners to 28 unforced errors.

Roddick, at the top of his game, showed his old buddy no mercy, slamming aces and clean volleys while whipping wicked winners. Fish said he thought it was the best Roddick had ever played against him. Roddick had three of his 10 aces in the last game, getting his fastest of the match - 228 kph — to set up match point.

When Fish couldn’t get the next serve back, there was no jubilation by Roddick. Both players, their heads down, trudged to the net where they shook hands and chatted briefly, each with an arm over the other’s shoulders.