* Olympic Athletes from Russia give up two-goal lead
* Slovakia win with third-period slap shot
* Slovakian defenseman gets biggest career goal (Adds quotes)
By Gabrielle Tetrault-Farber
GANGNEUNG, South Korea, Feb 14 (Reuters) - A third-period goal by Peter Ceresnak gave Slovakia a shock 3-2 win over the Olympic Athletes from Russia on Wednesday as the gold medal favourites squandered a two-goal lead.
Ceresnak capitalised on delay of a game penalty taken by Ivan Telegin, unleashing a slap shot from the point that beat goaltender Vasili Koshechkin to his left with just over 10 minutes to play.
Ceresnak, who plays in the Czech league, said his slap shot had been the most important goal of his career.
"This will help us win the next matches," the 25-year-old defenceman told reporters. "This is a tournament of big surprises."
The National Hockey League (NHL) decision not to release players for the Olympics in South Korea has made the Russians favourites to win gold.
Their team, composed of players from the Kontinental Hockey League (KHL), widely considered the world's second best, has more depth than other participating countries.
But former NHL player Ilya Kovalchuk, who had four shots on goal, said the team were struggling with their powerplay.
"We started well, we scored two goals and we could have scored more, but their goalie played well," Kovalchuk told reporters.
The Russians drew first blood as Vladislav Gavrikov and Kirill Kaprizov found the back of the net in the opening four minutes to jump in front 2-0.
But after a lightning start, the OAR lost their composure as Slovakia hit back with a pair of goals on four shots, including a breakaway by Martin Bakos.
"We were the ones who gave away the game," Russian head coach Oleg Znarok told a news conference.
After a scoreless second period, Slovakia took advantage of sloppy play by from the Olympic Athletes from Russia in the third as Ceresnak collected the winner on a powerplay off a second delay of game penalty.
The Russians next face Slovenia, surprise 3-2 winners over the United States, on Friday while Slovakia play the Americans.
Reporting by Gabrielle Tétrault-Farber; Editing by Steve Keating and Ed Osmond