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5/21/2014 12:59 A.M. ET

In big league debut, Rasmussen wins battle vs. Papi

BOSTON -- Before left-hander Rob Rasmussen made his Major League debut Tuesday night in Boston, he talked about the possibility of facing Boston's David Ortiz in his first game.

Rasmussen was promoted from Triple-A Buffalo earlier in the day because of his ability to get lefties out. The Blue Jays wanted to add another arm in an effort to match up with Boston during a three-game series, and it was Ortiz who was at the forefront of that discussion.

The 25-year-old Rasmussen admitted upon his arrival he was already thinking about the potential matchup. He had gone over various pitch sequences depending on the situation, and it turned out to be a good idea, because when the time finally came for Rasmussen to run onto the field, it was Ortiz who was waiting for him.

"I was fortunate enough that I got the call down, knew I was going to face Ortiz, so I was kind of able to prepare properly for him," said Rasmussen, who entered with one out in the seventh inning of Toronto's 7-4 victory. "Work on what I was going to throw him throughout the at-bat. Once you run in, it's just back to playing baseball."

Rasmussen began the at-bat with a pair of fastballs that missed the strike zone. Falling behind to one of the game's best hitters is kind of a nightmare situation for any rookie pitcher, but instead of wilting under the pressure, Rasmussen was able to pull himself together.

The California native came back with another fastball that found its mark. Rasmussen then got Ortiz to foul off a tough slider before inducing a ground ball to first on a curveball. With his job done, Rasmussen was then pulled from the game, but not before he got the game ball and a moment that will be cherished for years to come.

"I think it's just slowing down," Rasmussen said of his approach after falling behind 2-0. "At that point in the game, it's 7-4, no one on base, it's just, 'Hey, attack him here. See what he can do.' Obviously we know what he can do, but challenge him and see what happens. This time it happened for me, which is nice."

Hendriks or Redmond to start Saturday vs. A's

BOSTON -- Blue Jays manager John Gibbons said he expects to make a final decision on his club's No. 5 starter by Wednesday afternoon.

Toronto has been without a fifth starter since Dustin McGowan moved into the bullpen on May 15. Monday's off-day helped delay the need for a replacement, but the Blue Jays will need another starter for Saturday afternoon's game against Oakland.

The outing will go to either Triple-A Buffalo starter Liam Hendriks or Blue Jays long reliever Todd Redmond. It has been assumed for the past several days that Hendriks will ultimately get picked for the job, but Gibbons wasn't prepared to make it official.

"It'll either be Redmond or Hendriks," Gibbons said Tuesday afternoon in the visitors' dugout at Fenway Park. "We'll see how that all plays out."

The speculation about a possible promotion for Hendriks began late last week when general manager Alex Anthopoulos made the trip to Buffalo for one of his starts. Hendriks was claimed off waivers from the Orioles on Feb. 21, but the right-hander didn't receive much attention until he got off to a hot start with the Bisons.

The 25-year-old is 5-0 with an impressive 1.48 ERA in nine games for Buffalo. He has 36 strikeouts with three walks over 48 2/3 innings of work. The biggest selling point for Hendriks is his ability to throw strikes and the fact that he doesn't have to be stretched out in order to make the start.

Redmond has yet to make a start this season, and while he's tossed 24 innings, there also have been long periods of inactivity. The Blue Jays would have to ease Redmond into the role, and that's one of the main reasons the logical choice would appear to be Hendriks.

"Hendriks is stretched out, he's been starting down there," Gibbons said. "That's one reason it could be him. Red can do it. Red has thrown a lot, but it has been kind of sporadically. So we'll see.

"[Hendriks is] pitching pretty good down there, too, so it might be good to give him a shot. But we'll definitely know tomorrow, I would think."

Hendriks is the type of pitcher who has always excelled in the Minor Leagues, but he has yet to have much success in the Majors. He spent parts of three seasons with the Twins and has a 2-13 record with a 6.06 ERA in 156 career innings.

Rasmus has MRI; no return date set for Santos

BOSTON -- Results from an MRI on Tuesday afternoon confirmed the original diagnosis that Colby Rasmus has a strained right hamstring.

Rasmus is currently on the 15-day disabled list and hasn't played since May 12 vs. the Angels. He was sent for the precautionary MRI to rule out any type of major structural damage. With the results confirmed, the hope is that Rasmus will return by the beginning of June.

A return date for right-hander Sergio Santos is also unknown, but he's scheduled to resume throwing on Friday. Santos has been out since May 9 with a strained right forearm, but he will require more time than just 15 days on the DL.

Santos will need to throw at least a couple of side sessions before eventually going on a rehab assignment in the Minors. If there's any setback along the way, Santos could be out for a significant period of time. For now, things appear to be moving in the right direction.

"It won't be long," manager John Gibbons said. "He's going to start throwing the ball around when we get home. See where he's at. He said he's feeling good, I know that."

Worth mentioning

• Stroman allowed three runs on five hits in a start for Triple-A Buffalo on Tuesday afternoon. He struck out five and walked one while throwing 40 of his 64 pitches for strikes over the course of five innings. It was Stroman's first start since he was demoted to the Minor Leagues following Sunday's loss to the Rangers. The plan is for Stroman to receive at least a couple of starts in Triple-A before he receives consideration for a potential promotion.

Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.