Berra made 42 saves and Kris Russell scored at 1:32 of overtime, lifting the Calgary Flames to a 3-2 victory over the Chicago Blackhawks on Sunday night.
"I was really nervous, but right before the game when I was sitting in here," Berra said, "I just said, 'Go out, play your game and have fun. You have nothing to lose.
"I put that excitement and nerves into positive energy."
Russell's shot from the blue line clanked off the crossbar and past Blackhawks goalie Corey Crawford, ending Calgary's 10-game losing streak in Chicago. The Flames won at the United Center for the first time since March 2008.
"I saw a body in front and tried to get a hard shot off," Russell said. "I don't think he's seen it. Fortunately it went in."
"The last few games we've played well but haven't got rewarded," Russell added. "Tonight, we had a grinder-style game. Especially coming into a barn like this, I hope we can grab some momentum off this."
Mike Cammalleri and Curtis Glencross scored in regulation for the Flames. Calgary's T.J. Galiardi missed on a second-period penalty shot.
Chicago's Marian Hossa scored a power-play goal with 4:19 left in the third period to tie it at 2. Patrick Kane also scored for the Blackhawks, who had won three in a row.
Crawford made 27 saves.
The 26-year-old Berra was recalled from Abbotsford of the AHL on Saturday after the Flames waived Joey MacDonald. The 6-foot-4 Swiss goaltender was acquired in the trade that sent defenceman Jay Bouwmeester to St. Louis last April.
Berra was sharp against the Blackhawks, making a handful of point-blank and flashy stops.
"I'm very proud for Reto," said Flames coach Bob Hartley, who has coached in Berra's home country. "He played tonight the same way I saw him play a full year in Switzerland. Obviously, it's not the same calibre, but the poise he showed throughout the game.
"He never got rattled. The perfect control on every shot. The two shots that beat him were perfect shots. Great win."
After a slow start this season offensively, Chicago had scored 24 times in its previous five games. But the Stanley Cup champions showed little of that explosive skill and tempo against Calgary.
Although Chicago fired 44 shots at Berra, Blackhawks coach Joel Quenneville thought there weren't enough quality opportunities.
"We did put pucks at him, but we didn't get enough rebounds and we didn't get enough traffic," Quenneville said. "Certainly, he was pretty good at controlling those rebounds tonight as well."
The Blackhawks outshot the Flames 18-11 in the scoreless first. Berra coolly swept away Chicago's routine chances and turned in a couple of tough stops, including a quick glove save on Andrew Shaw with 5:00 left in the period.
Calgary's best chance came with 1:28 left, but Dennis Wideman's shot capping a 3-on-2 break was smothered by Crawford.
Galiardi was awarded his penalty shot — the first for Calgary and first against Chicago this season — at 4:06 of the second after he was hooked from behind on a breakaway by Hossa. He fired wide on the attempt.
Kane opened the scoring, beating Berra on Chicago's 23rd shot at 6:25 of the second.
After cutting across the top of the Calgary zone, Kane moved to the left faceoff circle and wristed a shot through a screen that fooled Berra on the short side.
Cammalleri tied it just 50 seconds later. Left open at the edge of the crease, Cammalleri was able to deflect Wideman's shot from the right point in midair and past Crawford.
Cammalleri has seven points in seven games since returning from an upper-body injury that sidelined him for the start of the season.
Glencross gave Calgary a 2-1 lead at 2:16 of the third on a shot that sailed past Crawford's glove, clanked off the right post and landed in the net.
Glencross cut in from left wing and gained a step on Chicago defenceman Sheldon Brookbank. He fired from the circle and Crawford fanned on a glove save attempt.
NOTES: Calgary also recalled D Chad Billins from Abbotsford, but he was a healthy scratch on Sunday. ... The Blackhawks were set to leave for Washington following the game, and will visit the White House on Monday to be recognized by President Barack Obama for their 2013 Stanley Cup title. ... Chicago C Michal Handzus missed his fifth game with an upper-body injury, but has resumed skating. ... Sitting out for Calgary were C Lee Stempniak (foot), D Mark Giordano (ankle) and D Chris Breen (abdominal).