World no 1 Roger Feder booked his place in the semi-finals with a straight sets win over Mario Ancic
Federer showed no trace of nerves against the last player to beat him at Wimbledon as he cruised into an early quarter-final lead.
Mario Ancic beat the Swiss star in straight sets back in 2002, but Federer showed all the grass-court nous which has brought him five consecutive titles at the All England Club since to take the first set 6-1.
Federer began in ominous fashion, producing a pair of aces and a backhand volley to hold the first game to love, then a sweet backhand pass from Ancic's first service point.
The Croat came to the net behind every point, but sent a backhand volley into the net to give Federer two break points - and did the same again to hand his Swiss opponent the game.
Ancic held his next service game and finally took a point off the Federer serve in game five, but it was the smallest of victories.
Federer held to 15 and passed Ancic at will in the next game for his second break of the match, before serving out to love to take the first set in 20 minutes.
Ancic started the second set more positively, holding his opening service game, but with the score at 1-1 play was suspended as the rain, which had delayed the start by nearly an hour, returned.
Play resumed on all courts and continued for almost half an hour despite specks of rain beginning to fall.
Shortly before 2.30pm, it became too heavy for play to continue and the covers were back on.
Play finally resumed after a delay of just over two hours and Ancic immediately looked to be in a better frame of mind - holding his first service game with only a double fault going in Federer's favour.
A rare Federer unforced error saw the next game go to deuce, but the 26-year-old pulled out two big serves when he needed them.
Ancic was made to battle in game seven, producing some stout defence before holding with his sixth ace, but Federer showed off his silky forehand to hold to love once more, levelling at 4-4.
At 5-5, Ancic netted a backhand volley to give Federer break point - and he duly handed the Swiss the advantage with a double fault.
And Federer served out to 15 to claim a two-set advantage.
Ancic had at least been competitive in the second set, but things threatened to get away from him when he fell 0-30 down straight away in the third.
An exquisite Federer passing return then made it 30-40 but he went long to take what proved to be a marathon game to deuce.
Ancic eventually held, but only after 16 minutes, when the deuce-count had reached double figures.
His next service game was a simpler affair - he held to love - and he appeared to have a chance to break in the following game as Federer slipped to 0-30, but the Swiss reeled off four straight points to hold.
And when Federer converted the first of two break points for a 3-2 advantage, there was no way back for Ancic.
The number one seed held to love in his next three service games to advance without even facing a break point.
He awaits the winner of the match between Feliciano Lopez and Marat Safin.