LIESTAL, Switzerland -- Rui Da Costa of Portugal broke away over the final six miles to win the eighth stage of the Tour of Switzerland on Saturday.
Robert Gesink of the Netherlands maintained the race leader's jersey, and seven-time Tour de France winner Lance Armstrong held seventh place, 55 seconds back.
Da Costa finished ahead of Caisse d'Epargne teammate Jose Joaquin Rojas with Belgian Maxime Monfort finishing third in the penultimate stage, a 107-mile ride from Wetzikon to Liestal.
Sunday's final stage is a time trial.
"We both worked together really well," Da Costa said. "In the end, that helped me to the victory. This is a great race and getting a stage win feels good. It was a hard day."
Luxembourg cyclist Kim Kirchen didn't start after having a heart attack on Friday night at his team hotel. The 31-year-old Kirchen was put in a medically induced coma at the Zurich University Clinic.
Team Katusha said in a statement that the rider is in a stable condition and tests so far have ruled out an infarction or a thrombosis. He will have to remain in a coma for at least 24 hours.
A group of breakaway riders that included Da Costa, Rojas and Monfort went clear near the 18-mile mark. With Monfort trailing Gesink by 5 minutes and 12 seconds in the overall standings before the stage, Gesink's team Rabobank organized the chase and didn't let the gap develop.
"It was a pretty hard day for the team, we worked well together and it was great to see," Gesink said. "I felt very strong. Tomorrow will be a close battle and I will try everything to win the Tour of Switzerland."
Working with Rojas, Da Costa finally broke away in the last climb. Rojas crossed the finish line 15 seconds back, while Monfort lagged 19 seconds behind.
A pack of favorites including Gesink and Armstrong was 1:16 behind.
Armstrong, who didn't speak to reporters after the stage, will face his last big test before next month's Tour de France in Sunday's 17-mile time trial around Liestal that starts with a seven-mile ascent.
Following a 3½-year retirement, Armstrong sealed his comeback with a third-place finish in last year's Tour, where his failure in the Annecy time trial ended his chances of winning.
Armstrong built his seven victories in the three-week showcase event with strong displays in the mountains and in time trials.
"I think in theory it's possible that Lance will win this race," said Johan Bruyneel, Armstrong's sports director at the RadioShack team. "But Gesink has a big advantage, his condition is great and he has a big morale."
Bruyneel said Armstrong has not had enough time to practice his time trial skills this year. The 38-year-old American was expected to compete in time trials at the Circuit de la Sarthe and at the Tour of California this season but had to withdraw from both events because of illness and a crash.
"He did one prologue in Luxembourg and one here but it was wet," he said. "He did some time trial work but it has been a catch-up constantly to find a good condition. But I think the condition is there now and I'm really happy with how things are going. I think he can do a good time trial tomorrow."