The lacrosse reserves did a double-take. Midway through the third quarter of the men’s lacrosse team’s 7-4 victory over No. 14 UMass Sunday afternoon at Reese Stadium, attackman Mike Karwoski ’09 finally turned up on the sidelines.

Rather than chastise him, head coach Andy Shay inserted Karwoski into the game right away.

“I got dressed in my lacrosse equipment on the way to the field — my Dad had picked up all my equipment,” Karwoski said. “I came out and started walking to the end of the bench, yelled, ‘Coach! Coach!’ He turned around, saw I was there, gave me the thumbs up, and he was ready to put me in.”

Why didn’t Shay hesitate? It’s because his starting attackman is no Rip van Winkle. He just doubles as a winger on the men’s hockey team.

As one of Yale’s most well-known two-sport athletes — and the first to play both hockey and lacrosse since Christian Jensen ’06, captain of the hockey team two years ago — Karwoski is used to the hustle of zipping from one event to another.

But February and March — when the two seasons overlap — can be overwhelming.

“I got up around nine o’clock thinking I was actually going to go to my lacrosse game,” Karwoski, who scored Yale’s final tally against the Minutemen, said. “I got a call from Coach [Keith] Allain saying, ‘We need you at practice this morning before you go to your game.’ I had a nine o’clock breakfast with lacrosse. Then I went to 11 o’clock lift with ice hockey, to one o’clock practice with ice hockey, and then went out and got in for the second half of our lacrosse game.”

Not everyone got the memo that Karwoski was planning to show up for the UMass game, though.

“I was carrying the ball on the field, and I saw him run on, and I was like, ‘Whoa, Mike’s here,’” attackman Brendon Gibson ’10 said. “I was going to pass it to the next person who I was supposed to pass it to and it was him. So I was a little weirded out. The first time I saw him was when I passed to him.”

Nor had Karwoski informed his hockey teammates, who are busy preparing for an ECAC first-round playoff series at Ingalls Rink this weekend.

“I just saw him hurrying out of the dressing room at the end of our practice,” center Blair Yaworski ’08 said. “Now I understand why.”

It seems fitting these days that Karwoski would be dashing out of Ingalls to make it to Reese, not the other way around.

Two years ago Karwoski burst onto the hockey scene with éclat. An agile skater blessed with the hand-eye coordination of a world-class table tennis player, Karwoski scored 17 points en route to winning the Ivy League Rookie of the Year award in the 2005-’06 season. In the otherwise humdrum final season of Tim Taylor’s tenure as Yale head coach, Karwoski was a welcome source of oohs and aahs — Sean Backman ’10 before there was Sean Backman. Taylor even engineered a power-play breakout that consisted of Karwoski skating the puck from end to end, like a nifty kick returner evading would-be tacklers.

But he has seen his ice time dwindle under Allain, playing in only 19 of the team’s 29 games this season.

When hockey is a source of stress, lacrosse has become a haven for Karwoski. After a tumultuous sophomore season under Allain, in which he played in seven fewer games and scored eight fewer points than the previous year, Karwoski started in all 11 lacrosse games he played, earning honorable mention All-Ivy honors along the way. A big reason for the rebound was Shay, Karwoski said.

“I’ve really gotten most of my confidence from coach Shay,” he said. “He’s really helped me out, put me out on the field in critical situations. He said, ‘Mike, I believe in you. I trust you.’ Even freshman year, sophomore year, he was telling me to be the big man out there on the field. ‘Get guys to follow you, put the ball in the net.’ And he’s really been a key factor for giving me a lot of confidence for my play — not only in lacrosse but keeping me positive for ice hockey as well.”

One of the problems with finding a place for a player like Karwoski is the uniqueness of his game. A similar player in both sports, Karwoski is offensive-minded, lightning-quick, heavily reliant on manual adroitness and given to a maverick playing style that sometimes alienates linemates. But hockey is an infinitely faster game than lacrosse. A hockey player would never report, like Gibson, that he was “supposed” to pass the puck to anyone; play is too free-flowing and rapid, and a player cannot hold the puck on his stick and shield it from an opponent while surveying the defense. Play in the offensive end in lacrosse is deliberate, allowing for coaches to call for highly specific set plays — to set players — including even a set sequence of passes.

“In lacrosse you can have very set plays because the play in the offensive zone is pretty relaxed,” Karwoski said. “And coach Shay has definitely put in a bunch of plays that are getting key guys the ball, including myself.”

On the ice, Karwoski meshed immediately with Yaworski when the two began playing together two years ago — prompting some in the Ingalls press box to dub them the Polish Line. When things are going well for Karwoski — like on Jan. 2 against UConn, when he twice set up a teammate for his first goal of the season — highlight assists come in bunches.

“He’s very unique with the puck,” Yaworski said. “You kind of just go to the net and expect good things to happen. I know he’ll fake defenders out — he even fakes me out sometimes — but I know if I go to the net the puck’ll be on my stick.”

Karwoski insists that he would never give up hockey, and Yaworski is among those who believe there are still many more highlights to come.

“With the new coach coming in, asking new things of us, certain guys filling different roles, and the fact that we’ve brought in new recruits and, in my opinion, better players, it makes competition for ice time that much greater,” Yaworski added. “But also, I think guys go in and out of their groove, and he may not have it right now, but he’ll find it before the end of the season.”