Just moments after being officially introduced as team captain, Jagr delivered a moment that predecessor Mark Messier would have been proud of. He needed just 29 seconds to net his first goal of the season and send the Rangers on the winning track.
Shanahan did him one better, scoring twice in his Rangers debut to become the 15th player with 600 NHL goals.
Wearing the "C" that Messier made famous, Jagr burst up ice during his first shift and scored on the initial shot of the hockey year.
Shanahan made it a rout. The milestone marker, that pushed him eight goals ahead of Jagr on the career list, came 2:58 into the third period when he scored from in front during a delayed penalty. Jagr raced to make sure the puck was secured and then handed it to Shanahan.
"It's always great when you play your first game and you're able to score your first goal for your new team," Jagr said. "He's over there. Go talk to him. It's his night."
It didn't start out that way.
Jagr took a pass from Martin Straka at his blue line and skated up ice toward the right side of the Capitals zone. He cut inside, drifted toward the right circle and worked around defenseman Shaone Morrisonn before letting go a hard shot that found the low right corner behind Olaf Kolzig.
The 24th captain in Rangers history was swarmed by teammates as Madison Square Garden rocked. Chants of "M-V-P" rained down on Jagr, who finished second for the award last season.
"That first shift, what he did is he told everyone in the NHL he is the captain of the Rangers," said Shanahan, picked as an alternate.
Renney used only alternate captains last season, the first following Messier's retirement after the NHL lockout. But during the team's first trip to the playoffs since 1997, Renney cited a noticeable leadership void when the Rangers were swept in the opening round by New Jersey.
Jagr was the obvious choice to take over in his third season in New York. Once Renney was convinced the Czech star wanted the job and was ready for it, he had the "C" sewn onto Jagr's left shoulder -- the one injured during the playoffs.
Now healthy, Jagr jump-started the Rangers again, first by skating out of the smoke-filled tunnel as his captaincy was announced and then with his stick that produced 54 goals and 123 points last season.
"We didn't want to have a big ceremony about it," Jagr said. "He just wanted to make it easy for me."
Shanahan and Blair Betts scored 1:34 apart in the second period to break it open, Straka had an empty-netter, and Henrik Lundqvist made 25 saves for the Rangers, who won a home season opener for the first time since 1985 -- also against Washington.
Alexander Ovechkin drew the attention of the Rangers, who kept the reigning rookie of the year in sight throughout. He drew reaction from the crowd with his skating, hard-hitting and imaginative offense, but was kept scoreless.
The Capitals went 0-for-8 on the power play, and Ovechkin was on the ice for four goals against.
"We made lots of mistakes on the power play," he said. "We must work on it. We had lots of chances. We must score.
"I don't know what happened to our line."
Kolzig began his 16th season with the Capitals in fine fashion, stopping 31 shots - 16 in the second period.
After Semin sneaked a shot between Lundqvist's legs to tie it, the Rangers struck back.
Adam Hall pounced on a Washington turnover and passed to Betts, who wristed a high shot past Kolzig with 7:07 left in the middle frame.
Following another turnover, Petr Prucha rifled a pass up the middle of the ice to Shanahan, who broke in alone and snapped a shot between Kolzig's legs to make it 3-1 at 14:27.
- Jagr was the first Rangers player to score in the first minute of the season opener since Ron Greschner on Oct. 11, 1984.
- The Capitals haven't won at MSG since Jan. 28, 2004.
- Kolzig has played in 37 of 38 games against the Rangers, dating to Jan. 9, 1997.
- Prucha had two assists.