Roger Federer lost his first set of the tournament, but it was little more than a glitch as he continued his imperious route to what is looking increasingly like his seventh Wimbledon final. This time his victim was Germany's Philipp Kohlschreiber, who battled defiantly on Centre Court but still went down to a 6-3, 6-2, 6-7 (5/7), 6-1 defeat. It was a display scarred by a couple of lapses of concentration, especially in the third set, but they will have given scant comfort to the rest as Federer took his place in the fourth round with the added bonus of a couple of days rest over the weekend to recharge his energies. Federer, who now plays Robin Soderling in the fourth-round, the man he beat recently in the French Open final, said: "It has been a good first week. I thought this was my best match of the tournament even though I lost a set. It's fine as long as you come through without losing too much energy "It will be nice to have Saturday and Sunday off and get rid of the pressure for a day or so. I felt a lot of pressure two years ago but I feel relaxed now. It's going to be an exciting second week." The first game of the match epitomised the form Federer is in right now. Four first serves, two aces. He went on to reel off the first four games with two breaks of serve. Federer looked in superb form but Kohlschreiber to his credit dug in, stepped up the aggression and managed to break serve in the next game and when the German won the next too, it looked as if Federer might have lost momentum. It was not to be, Federer staying solid, but there was a brief glimpse of frustration from the Swiss at the start of the second set when his groundstroke landed flush on the line only to be called out by the line judge. Federer threw his arms wide, appealed and Hawkeye confirmed the great man's eyesight to be somewhat keener than the official's. He went on to break the Kohlschreiber serve and the match at that stage was beginning to take on the air of a training stint. Another break of serve in the fifth game ended the set as a contest, with the Federer sliced backhand a particular feature. The third set was the best of the match, at last the contest was competitive with Kohlschreiber digging in after once more losing his serve in the first game. The rallies became heavier and longer and Kohlschreiber gained more joy at the net, reclaiming the break of serve in the eighth game. He took the set to a tie-break which he won when Federer pushed an easy forehand just wide. A murmur went round Centre Court as Federer, for the first time this tournament, looked fallible. It did not last long, Kohlschreiber again losing his first service game of the set and with it the initiative.