KRASNAYA POLYANA, Russia (AP) -- No one knew quite what to expect from Dario Cologna at these Olympics.
It did not take long for the Swiss cross-country skier to provide an emphatic answer.
Cologna won the men's 30-kilometer skiathlon at the Sochi Games on Sunday with the strongest finish of any racer in the field, pulling away from his rivals at the top of the last uphill section before holding off defending champion Marcus Hellner of Sweden on the final straight.
It was quite an achievement for someone who had surgery in November to repair an ankle ligament and only returned to competition last month.
"It's a very big day, and very emotional for me to come back and win a gold medal, my biggest thing I won so far," said Cologna, who won gold in the 15K freestyle in Vancouver. "I said I hoped to be at my best again before the end of the Olympics, but it can't get better than this."
Cologna finished in 1 hour, 8 minutes, 15.4 seconds, with Hellner was 0.4 seconds behind to win silver.
Martin Johnsrud Sundby of Norway beat Russia's Maxim Vylegzhanin in a tight sprint for the bronze that led to a protest from the Russian team. They argued the Norwegian had impeded his rival by crossing into his lane just before the finish line.
A jury upheld the results but gave Sundby a written reprimand, saying he had broken the rules but did not affect the results. The Russian team can still appeal the ruling to the International Ski Federation's appeals committee.
Sundby acknowledged he crossed into Vylegzhanin's lane, but said he didn't realize what had happened until after the finish.
"I feel bad about the whole episode," Sundby said. "This was never, ever my intention. I didn't know where I was. Luckily it didn't influence the results. ... I feel really upset about it."
Cologna is a three-time overall World Cup winner and the only Swiss cross-country skier to take home an Olympic gold. He is also the reigning world champion in the skiathlon, which mixes classical-style skiing with freestyle, but came to Sochi with low expectations following his injury.
By finishing second in a World Cup race last weekend, Cologna send a signal he was returning to form. He left no doubt Sunday that he's back to his best, even if his foot is "still not 100 percent."
"When I am sprinting like this, I still feel it a little bit," Cologna said. "Who cares, I won a gold medal and I am in a very good shape beside my foot. I did a lot to be ready here. It was not an easy season."
Cologna stayed well back in the pack for most of the 15K classical style portion of the race before moving his way up the field after the switch to freestyle at the halfway point.
About 15 skiers were still in the main pack entering the last two kilometers, but when Hellner made a move up the steep hill just outside the stadium, only Cologna, Sundby and Vylegzhanin could keep up.
Cologna then pulled in front near the top and immediately opened up a gap of about 10 meters over Hellner. The Swede pulled closer in the final sprint but couldn't catch his Swiss rival.
"Dario was a little bit stronger, I couldn't follow him," Hellner said. "I felt a bit stiff in the legs at the end. I regained my strength again, but he was too strong."
Unlike Cologna, double Olympic champion Petter Northug of Norway looked far from having found his best form as he ran out of energy on the final hill, dropping back and out of contention. Northug is a two-time world champion in the skiathlon, but has struggled with an illness this season and Sunday's performance was a worrying sign for Norway's biggest star on the men's side. A lethargic-looking Northug skied down the final straight at a slow, walking pace and he ended up 17th, 1:24 behind Cologna.
"My feeling today was that I didn't have the power I needed to fight in the top three," Northug said. "In the last climb it was just to give up and save power for the (individual) sprint."
The freestyle sprints are held Tuesday for men and women.