Montañez, Gaub and infielder DJ LeMahieu were called up from Triple-A Iowa and added to the Cubs' roster on Tuesday. Manager Mike Quade said he'll mix and match with the new additions.
LeMahieu, a second-round pick in 2009, and Montañez, who was the Cubs' first-round selection in 2000, were both called up during the season. Gaub has yet to make his big league debut.
"After [Monday's] game, they called me, DJ and Louie in at the same time to kill three birds with one stone," Gaub said. "That was exciting. I was the first one in there, and I'm the only guy who had a first-time callup. It was kind of anti-climactic, because I knew it was coming. But it was exciting. It still hasn't sunk in.
"It's been exciting, just calling family and friends," he said. "People who I haven't had a chance to call have been calling me."
Gaub, 26, was acquired from the Indians in the Mark DeRosa deal on Dec. 31, 2008. At Iowa, the lefty posted a 3.42 ERA in 50 games, and was 7-for-11 in save opportunities. He struck out 75 over 55 1/3 innings, an average of 12.2 strikeouts per nine innings, and limited opponents to a .209 batting average.
In five Minor League seasons, Gaub is 12-12 with 17 saves and a 3.60 ERA.
"I had a much better year this year than last year," Gaub said. "I struggled on the mound and battled injuries last year, too. This year, I pitched well. I pitched in the All-Star Game, the first one of my career. I just did well. I was consistent all year, and they rewarded me with this callup.
"They see something in me. They gave me a chance. Hopefully, I can get some opportunities and do well to show some people that I can help the team out."
LeMahieu, 23, a right-handed batter, began the 2011 season with Double-A Tennessee, and hit .358 with 15 doubles, two triples, two home runs, 32 runs scored and 27 RBIs in 50 games. He was promoted to Chicago on May 30, then optioned to Triple-A Iowa on June 28, and hit .286 with seven doubles, three home runs and 23 RBIs in 58 games.
Combined, LeMahieu batted .319 in the Minors this season, with 22 doubles, three triples, five home runs and 50 RBIs in 108 games.
Montañez, 29, batted .321 in 92 games with Iowa, hitting 22 doubles, seven triples and seven homers, while driving in 69 runs. He hit .400 against lefties, .285 against right-handers.
"It's always nice to come back and contribute a little bit," Montañez said. "[I'm trying] to finish strong, finish on a positive note and help the team win."
Montañez spent seven seasons in the Cubs' Minor League system before joining the Orioles prior to the 2007 season. He made his big league debut with Baltimore in 2008, and spent parts of three seasons in the big leagues with the Orioles (2008-10), before signing with the Cubs as a Minor League free agent with an invitation to Spring Training in January.
He does know his way around the clubhouse after his brief callup this year.
"It's the same as in the Minor Leagues," Montañez said. "Just play hard and do the best you can."
While with the Cubs earlier this year, LeMahieu batted .243 in 23 games, while Montañez hit .239 in 25 games from May 24-July 2.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter@CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.