Pat Rafter lined up an Italian Open semi-final with Spain's Felix Mantilla in Rome yesterday after roaring back to beat Ecuador's Nicolas Lapentti 4-6, 7-5, 6-1.

The other semi-final pitches Spaniard Alex Corretja, who came back from match point to beat Argentinian Franco Squillari 5-7, 7-6 (7/4), 7-5, against either Slovak Karol Kucera or Brazil's Gustavo Kuerten.

Rafter, winner of the last two US Opens and attempting to become world number one, struggled with his service in the opening set, but improved in a tight second, coming from 2-0 down to lead 3-2, before cruising the third.

It was a fully-deserved win for the fourth seed, whose best results before Rome were two third-round appearances, and he pointed to early in the second set as the turning point.

"He had break point at 2-2 to go up a break and that would have been another kick in the head if he'd won that," said the Aussie.

Rafter admitted, though, to being surprised by his progress in Rome.

"It's a big surprise for me so far. It's a Super Nine, we've had all the top guys here, and I've come in with very little form."

If he wins the tournament, Rafter will become the second Australian to be world number one - 25 years after John Newcombe.

Meanwhile, Serena Williams was forced to retire from her quarter-final match with fourth-seeded Arantxa Sanchez-Vicario at the German Open in Berlin yesterday with a strained right elbow.

Steffi Graf also failed to advance beyond the quarter-finals when she was defeated 5-7, 6-4, 64 by Julie Halard-Decugis of France, while eighth seed Patty Schnyder of Switzerland was upset by Ruxandra Dragomir when the unseeded Romanian rallied for a 3-6, 6-1, 6-1 win.

Top seed Martina Hingis also struggled in the second set, recovering from 2-5 and saving four set points against Austria's Barbara Schett before advancing 7-5, 7-5. It is the first time in four attempts that Hingis has gone beyond the quarter-finals.

In the semi-finals, Hingis will play Sanchez-Vicario and HalardDecugis faces Dragomir.