OAKLAND -- Veteran pitcher Bartolo Colon is out of the rotation and will be replaced by rookie right-hander Adrian Sampson on Tuesday against the Angels.
Manager Jeff Banister said Colon will work out of the bullpen, possibly for the rest of the season.
"We made a decision to give Sampson a start," Banister said. "We'll see where that takes us."

Sampson was a September callup after going 8-4 with a 3.77 ERA in 19 starts and 14 relief appearances at Triple-A Round Rock. He was once a highly regarded prospect with the Pirates and Mariners before being set back by a torn flexor tendon. It took him two years to get back to the big leagues and now the Rangers want to take a look at him.
Colon, 45, is in his 21st season and will be a free agent this offseason. He achieved his goal of settting a new record of 246 wins by a pitcher from Latin America. He still wants to pitch next season, but said after his last start he'll make a final decision this winter.

Colon began the year by going 2-2 with a 3.55 ERA and a 0.93 WHIP in his first nine starts and two relief appearances. Opponents were hitting .221 off him. But he is 5-10 with a 7.11 ERA and a 1.62 WHIP in his last 14 starts. In that stretch, opponents are hitting .328.
"First of all, we have celebrated everything Bartolo has done during the season," Banister said. "Not only on the field, but in the clubhouse. The thing I'll acknowledge is every player -- whether they are a first-year player or a decorated and celebrated player -- they all want to be on the field competing. It's not always an easy conversation to talk to a player who has done the things that Bartolo has done.
"We are at a spot where we have some players that we would like to take a look at that we haven't seen at this level."
Yovani Gallardo will stay in the rotation and is scheduled to pitch on Wednesday against the Angels. He can also be a free agent after the season, but there could be mutual interest in him returning to the Rangers next season. He is 8-4 with a 5.45 ERA and a 1.49 WHIP in 14 starts since being called up from Triple-A.
"We are taking a look at everybody on our team," Banister said. "We have had guys who have been here for a while and guys who were called up in September. We are trying to do the best we can to look at these guys in all situations."
Rangers beat:
• Banister said outfielder Willie Calhoun will be in the lineup on Sunday. He has been dealing with a chest cold since being called up on Tuesday.
• Going into Saturday, Rangers hitters had been hit 77 times and have a chance to break the club record of 81 set last year.
• Joey Gallo hit his 35th home run on Friday after hitting 41 last year. Gallo, 24, is the second Rangers player to have multiple seasons of 35 or more home runs prior to his 25th birthday. Juan Gonzalez did so in 1992-93. The four active players who did so were Jose Pujols, Manny Machado, Michael Trout and Giancarlo Stanton.