Shaun White declared the Sochi halfpipe nightmare over after opening his bid for a third straight Olympic title by storming into the final with the best score in qualifying on Tuesday.

The American brushed aside concerns about the quality of the pipe with a stunning display of tricks for a score of 95.75 on his first run.

The 27-year-old, who withdrew from the slopestyle event in case an injury jeopardised his triple gold bid, earned a more modest 70.75 on his second run but a place in the last 12 who will contest the final later on Tuesday was never in doubt.

"The pipe is riding much better than yesterday," he told Reuters.

"I'm really happy just to put some runs down.

"Yesterday was a nightmare and it's so much better to wake up and discover it was all a dream."

White was joined in the final by compatriot Danny Davis, who had described the pipe as "garbage" after training on Sunday.

Davis's score of 92.00 was bettered by two Japanese, Ayumu Hirano topping the leaderboard in the first heat in 92.25 and Taku Hiraoka finishing just behind White in the second qualifying run in 92.25.

Swiss boarders Christian Haller and David Habluetzel secured the other two spots in the final, leaving expected medal contenders Greg Bretz of the United Statesand Iouri Podladtchikov to battle it out in the semis.

Finn Peetu Piiroinen, who won silver behind White in Vancouver four years ago, failed to start the second heat.

The competition got underway on schedule on Tuesday after organisers sought help from the team that prepares the Alpine skiing runs to improve the course.

Warm weather had turned smooth packed snow into a rut-filled slushy tube, slowing the snowboarders down and preventing them from getting the big air they need to perform their best tricks.

"They salted and watered (the pipe) after we called in help from the alpine team. It was a matter of firming up the snow," International Skiing Federation (FIS) spokeswoman Jenny Wiedeke said.

"We used something similar to an infield sprinkler in baseball because we don't want the pressure of the water to leave indents in the snow."

Some riders felt that some problems remained.

"They are far better than they were in training but our edges are still sinking into the wall," said Britain's Ben Kilner, who finished 16th to miss out on qualification.

"We just have to go big and just make sure we don't fall but the higher you go, the more likely you are to make an error."