Roger Federer's quest for a record-breaking eighth Wimbledon title continues apace after victory in the Swiss derby on Centre Court yesterday, where Basel defeated Lausanne 3-6 7-6 (7-5) 6-4 6-4.
Tomorrow's semi-final will be Federer's third match in four days, but playing for the third time on successive days caught up with his compatriot Stan Wawrinka, who had complained in vain about the scheduling after his third-round match was held over to Monday because of rain.
He sought medical assistance after losing the second set, then never looked himself again and was playing from memory by the time he managed to save four match points but not a fifth.
Davis Cup team-mates and Olympic gold medallists together they may be but until losing energy Wawrinka was in no mood to defer to the older man, whom he overtook as Swiss No 1 after winning the Australian Open in January.
Beating Federer in their most recent meeting in Monte Carlo this year encouraged his self-belief too, even if it left him 13-2 behind on head-to-heads.
That was carried into the first set, won by Wawrinka in only half an hour and it was just one mistake that cost him the second.
At that stage Wawrinka called for assistance and took some pills for an unspecified ailment, after which he began to look a little more sluggish. By the time they took effect the third set had gone and the fourth also required only one decisive break of serve.
"Stan played great, especially in the first two sets, then started to struggle," Federer said.
"He was hitting the ball too cleanly for me to do anything with it. I don't want to get too far ahead of myself but it's good to be back in the semi-final."
He has played eight at Wimbledon and not lost one yet.
If anything was going to let Wawrinka down it was a first serve that hit the spot barely 50 per cent of the time.
Considering that, Federer was able to force few break points for a long time. In the first set he was allowed only one, failing to take it after having fallen behind to a break in only the fourth game.
A smash from Wawrinka after Federer tried to lob him brought three set points, the second of which was gleefully accepted.
It meant Federer had dropped a set for the first time here this year and he was in no mood to do so again. Serving first this time, the former champion was able to hold comfortably and theoretically keep the pressure on, although without coming close more than once to a break.
So a tie-break it was, in which one crucial mistake by Wawrinka, sending a forehand too long, allowed his opponent to serve and volley for 7-5 and equality.
In the third set Wawrinka's service games became more erratic and after saving two break points at 1-1, he failed to do so at 3-3. Federer was on top and the shot to seal the set was an emphatic one, smashed from overhead.
Federer, merciless, kept Wawrinka running from side to side, up and back, and made the break early for a 2-1 lead, quickly extended and consolidated to earn yet another Grand Slam semi-final against Milos Raonic.
It will be Federer's 35th, a record, and only Jimmy Connors has won more matches here (84-72).
Raonic swept past Nick Kyrgios to book a maiden grand slam semi-final against Federer.
The eighth seed eased past 19-year-old Kyrgios 6-7 (4-7) 6-2 6-4 7-6 (7-4) yesterday.