ATLANTA -- Even the NHL's youngest player can see the Edmonton Oilers are running out of time to make a move in the Western Conference.
The 18-year-old Gagner gave the Oilers a 2-1 advantage late in the second period, only 1:06 after Slava Kozlov scored a tying goal for the Thrashers.
The Oilers and Thrashers each have 49 points. Atlanta is only one point out of the lead in the weak Southeast Division, but Edmonton is still last in the Northwest Division and 14th in the Western Conference playoff standings.
"Every game is like a playoff game for us right now," Gagner said. "We're fighting for our lives. I think everybody realizes that."
"Our young guys played well," Edmonton coach Craig MacTavish said. "They're a highly skilled unit. They were the difference in the game."
Gagner has four goals, all in road games. He leads the NHL with four shootout-deciding goals, and treated his scoring opportunity against Thrashers goalie Kari Lehtonen much like another one.
After taking a pass from Steve Staios, Gagner faked toward the left side of the net. After Lehtonen bought the fake and lunged in that direction, the rookie center lifted the puck over the goalie into the exposed right set of the net.
"I knew I had lots of time," Gagner said. "A lot of room opened up for me. It looked pretty much like I had an open net."
Gagner was Edmonton's first pick, and the sixth overall, in the 2007 draft.
"I didn't think I'd be here this young," Gagner said. "I didn't know when the opportunity would come.
"I just wanted to prove I belong."
"It's a huge win for us," Roloson said. "We're battling to get into the playoffs."
Kozlov's goal, on a set up from Eric Perrin, tied the game with about five minutes left in the period.
After Gagner gave Edmonton the lead, Gilbert scored 4:20 into the third period to increase the lead to 3-1. Nilsson scored from the left circle with 6:03 left in the period.
All-Star selection Marian Hossa scored with 1:20 left for Atlanta.
The Thrashers, who gave up the most goals in franchise history in a 10-1 loss at Buffalo on Friday, have lost three in a row.
"We played horrible against Buffalo, but I think we played one of our best games of the year today," Lehtonen said. "Edmonton maybe had five or six scoring chances all game. ... It seems they got the puck in every chance they had."
Atlanta coach Don Waddell noted his team helped both Buffalo and Edmonton end losing streaks.
"I've said it before, when we respect our opponent we play better, and I don't know how we don't respect anyone at this point," Waddell said.
"When we face teams that are going good, we usually come up with a better effort and that's certainly something we need to address."
Atlanta's Ilya Kovalchuk was held without a goal for the fourth game in a row. The NHL leader with 37 goals, Kovalchuk had not gone more than two games without a goal this season before the current slump. He does not have a point in three consecutive games.
Oilers defenseman Dick Tarnstrom had three penalties, including a four-minute penalty in the first period for high-sticking.
"He had one of those games where you hope the team can put together a solid effort and bail you out," MacTavish said. "We bailed him out of what was a tough game."
- Hemsky, Staios and Shawn Horcoff each had two assists for the Oilers.
- Edmonton D Matt Greene returned after missing 34 games with a broken ankle. He sustained the injury on Nov. 30.
- Edmonton made its first visit to Atlanta since Dec. 8, 2002.
- D Joel Kwiatkowski, recalled from AHL Chicago on Saturday, earned an assist on Kozlov's goal for his first point with Atlanta.
- Roloson (8-12-4) earned his first win since Dec. 13 at Detroit.