ATLANTA — The Atlanta Thrashers had to wait to find out how costly their slump-ending victory over Pittsburgh would prove to be.

The Thrashers lost star Ilya Kovalchuk to a knee injury while ending a five-game losing streak in Wednesday night’s 4-1 victory over the Penguins. How badly hurt Atlanta’s leading scorer was couldn’t immediately be determined.

In his first game since Sunday’s All-Star game, also at Philips Arena, Kovalchuk scored his 38th goal but was injured in a knee-on-knee hit from Pittsburgh’s Jarkko Ruutu in the second period.

Kovalchuk made a brief return later in the frame for one shift. He missed the third period and will be examined by team doctors on Thursday.

"You can’t keep him off the ice," Thrashers general manager and coach Don Waddell said. "He was determined to come out and at least test it.

"These kind of injuries, you always wait until the next day and see how the swelling is and just see how he reacts from it."

Kovalchuk was leveled by Ruutu 3:21 into the second period. The collision left Kovalchuk laying on the ice in obvious pain in front of Atlanta’s bench before he limped to the locker room.

Atlanta’s Steve McCarthy immediately followed the collision by crashing into Ruutu and then punching the left winger while having him pinned against the boards in front of the Thrashers bench.

McCarthy earned a minor penalty for instigating, a major for fighting and a misconduct. Ruutu drew a pair of majors for kneeing and fighting, and was ejected.

Ruutu defended the hit as an intended routine check.

"I meant to finish my check," Ruutu said. "He ducked away and I barely hit him. I didn’t change direction. I just went for a hit.

"I got five minutes for fighting and I didn’t even throw a punch. I had my gloves on the whole time."

McCarthy said Ruutu was "a good teammate" when the two played together in Vancouver, but he said Ruutu had to answer for the hit on Kovalchuk’s knee.

"When he takes a liberty like that, it’s unacceptable," McCarthy said. "He plays his game well, but when he takes advantage of one of our best players, that’s unacceptable."

When asked if he was concerned about a possible suspension, Ruutu said "There’s no reason to be suspended for that hit."

Waddell praised McCarthy for defending Kovalchuk.

"Absolutely. I congratulated him after the game because I think our team arose from that," Waddell said. "When one of your best players gets hit like that, and then your player jumps in like that, that’s a penalty we will kill all the time.

"To stick up for your teammates, I’ll never have a problem with those kind of penalties."

Kovalchuk made only a brief return. He took the ice for a shift with about 5 minutes left and appeared to favor the knee. He headed straight to the locker room after he left the ice.

The Penguins fell to 2-2-1 since losing captain Sidney Crosby to a high ankle sprain. Pittsburgh won 4-2 at New Jersey on Tuesday night in its first game following the All-Star break.

Kari Lehtonen stopped 29 shots, losing his shutout bid when Ryan Whitney scored for Pittsburgh with 8:42 left.

Kovalchuk and Bobby Holik scored first-period goals and Eric Perrin and Jim Slater added tallies in the third to give Atlanta a 4-0 lead.

Perrin scored an unassisted, short-handed goal 1:32 into the period, and Slater scored about 2 minutes later. That prompted Pittsburgh coach Michel Therrien to pull Ty Conklin, who stopped only 16 of 20 shots, and replace him with Dany Sabourin.

The Thrashers avoided matching their worst losing streak of the season, the 0-6 start that cost coach Bob Hartley his job.

Holik scored on a rebound shot past Conklin 7:08 into the opening period.

Kovalchuk, held without a goal in the All-Star game, quickly ended his longest streak of the season without a point. Kovalchuk found the net during a power play when he sent in a shot from well back of the circles with just over 3 minutes left in the first period.

Kovalchuk’s goal came near the end of a double-minor against Jeff Taffe for high-sticking.

Kovalchuk had gone four games without a point and five without a goal, not including his one-game suspension last week for checking New York Rangers defenseman Michal Rozsival from behind.

The Penguins had an apparent goal disallowed following a video review with 2:10 left in the second period. The replay showed Nathan Smith kicked the puck into the net.