Roger Federer clinched his 20th successive victory while Rafael Nadal produced his best performance of the Qatar Open as the two great rivals came within one round of a showdown in the opening week of the season.
Federer's was an up-and-down effort in a 6-3, 5-7, 6-4 success against Andreas Seppi, the eighth-seeded Italian, but Nadal had to be close to his muscular, tenacious best to see off the challenge of Russian Mikhail Youzhny in Thursday's quarter-finals.
The Grand Slam record-holder from Switzerland and the French Open champion from Spain will have their 27th encounter if they both win again, but predictions are unwise in the uncertain early days of a new tour.
What does seem likely is that Nadal is overcoming some of the disadvantages of his limited off-season preparation -- only five days work with a differently balanced racket -- and is beginning to build for tough performances at the Australian Open.
He served stridently and with a high first serve percentage, moved as superbly as ever, and was both consistent and aggressive in some brilliantly long drawn out baseline rallies.
He needed to be. Youzhny, often one of the most fluent strikers of the ball off the ground, looked in tremendous touch, attacking dangerously from both wings, mixing slice with topspin on the backhand, and coming forward more than he used to.
Even when he went two breaks down in the second set, he nearly erased the deficit, holding four break back points for 5-5 before Nadal closed it out with a heavy first serve, a bold forehand approach and a rock-solid volley.
That seemed like a blue-print of the Nadal into which he is trying to evolve, and he was as pleased with his performance as the crowd had been delighted.
"I think I played really well," he said. "At the end of the match I was a little bit nervous. But for the rest of the match I am very, very happy. I am feeling a bit better every day.
"I think I was moving fast and going to the net a lot of times and this is what I need to keep doing if I want to compete against top players."
Federer started well against Seppi, but then the top 40 Italian began to rally elegantly and expertly from the baseline.
The defending champion also played a little ambitiously even for him in the second set, going 1-5 down, and recovering to 5-5 before somehow still losing it.
He broke serve early in the third set and held the advantage till the end, but his excellent first serving and passages of brilliance were marred by a total of 41 unforced errors.
"The third was pretty close and I am happy to get through," said Federer. "I am relieved to be in the semi-finals."
He will have another match with Jo-Wilfried Tsonga, whom he overcame in last year's semis, before losing to the Frenchman in the Wimbledon quarter-finals, and narrowly beating him again in the final of the ATP World Tour finals in London.
"I am looking forward to playing him again," Federer said. "I hope it will be a good season for both of us.
"He's always a nice guy to see play, and a nice guy off the court as well -- so I hope we can live up to expectations."
Nadal also has a French semi-final opponent -- Gael Monfils, the Switzerland-based Parisian who is a former finalist, and who will ensure a contest between arguably the tour's two best athletes.
Monfils produced a display of heavy first serving and bounding court coverage which was too much for Viktor Troicki, the improving fifth-seeded Serbian, whom he outplayed 6-2, 6-3.
"It will be difficult to play Rafa but I will try to play against him like I did tonight," said Monfils. "At least I know what he will give me, so maybe I can do something about that."
Nadal may again be supported by his friend Raul, the former Real Madrid footballer who came to watch his match with Youzhny.