Roger Federer says he will never be in favour of the "hawkeye" replay equipment to decide line calls even though the technology helped him to a 7-6 7-6 victory over Robin Soderling in the Madrid Masters on Thursday.

The world number one successfully challenged the calls on the final two points of the second tie break to beat the dogged 22-year-old Swede.

"It wouldn't have made a difference to the score in the end," Federer told a news conference. "Without hawkeye I would have broken him in the first set because the call would stand.

"So I would have won the first set probably easier. It turned out to be a crazy end (to the match). I thought it was really funny, especially waiting for the match point. This has never happened before."

Players have the right to challenge two line calls per set and another in the tie break. If they are correct they keep their entitlement to challenge intact.

Asked if Thursday's experience meant that he would change his mind and make him in favour of the equipment, Federer replied: "It won't. I will never be."

The 25-year-old Swiss, who is bidding for his 10th title of the year in Madrid, was pushed hard all the way by Soderling and said his experience of pressure situations was the key to his victory.

"He hung in there and it got really close and anything is possible in the tie break. I think that I was always putting on the pressure though and that was maybe why he double-faulted in the first tie break and crumbled in the second.

"The hard work does pay off eventually but I had to play well today, that's for sure. I think an experienced player has an edge and that's what I am. That can sometimes work in your favour because you've been in pressure situations."

Federer now faces a quarter-final against unseeded American Robby Ginepri who had a 6-3 7-6 victory over world number eight Tommy Robredo.

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