TAMPA, Fla. -- This is why the Phillies signed Spencer Turnbull.

Taijuan Walker is likely to open the season on the 15-day injured list after he reported something wrong with his right shoulder on Saturday. Walker was scheduled to throw a bullpen session in the morning at BayCare Ballpark, but something felt amiss while he played catch. The Phillies shut him down and sent him for testing.

“Anytime a guy has something like that this late in the spring, you’re a little bit concerned,” Phillies manager Rob Thomson said.

Thomson said Walker did not describe pain in the shoulder.

“He just said it didn’t feel right,” he said.

Walker entered the final week of camp already behind schedule because of time missed for personal reasons and right knee soreness. Now, he will miss his final scheduled spring start Monday in Clearwater. Walker got hit hard Wednesday against Baltimore, allowing seven runs in 2 2/3 innings. He has been struggling to build velocity all spring, which might or might not be related to the shoulder.

“Maybe he was trying to grind through it,” Thomson said.

The Phillies will know more on Sunday.

If Walker cannot pitch, Turnbull will take his place in the rotation. Walker was scheduled to pitch April 1 against the Reds.

“That’s why you have all the depth,” Thomson said.

The Phillies signed Turnbull to a $2 million contract in February because they knew they needed to improve their starting pitching depth. He got to camp last month as a candidate to be a long man, although he could have started the season with Triple-A Lehigh Valley.

The Phillies had expressed some interest earlier this year in free-agent left-hander Jordan Montgomery on a one-year deal, but that interest cooled as camp got going. It is unclear if Walker’s shoulder issue might change their thinking, although sources said earlier that the club always felt it would need to clear payroll to keep from crossing the third luxury tax threshold.

Turnbull was scheduled to pitch three innings out of the bullpen Saturday because the team has been trying to get him acclimated to pitching as a reliever. Turnbull has appeared in relief only once in 61 career games.

But once Walker went down, the Phillies changed their plans to get Turnbull ready to start.

It went well. Turnbull allowed three hits and struck out five in three scoreless innings during a 6-6 tie with the Yankees at George M. Steinbrenner Field. He threw 51 pitches (34 strikes).

Turnbull has put himself in a good spot to make the team, especially with Orion Kerkering opening the season on the 15-day injured list following a lengthy absence from an illness earlier this month. It means the Phillies might need not only a replacement for Walker in the rotation, but three relievers, too.

“I have not heard anything officially from Topper, but I feel pretty good about my chances at this point,” Turnbull said. “I haven’t had an official conversation yet.”

Luis F. Ortiz (3.00 ERA, nine innings) and Yunior Marte (0.00 ERA, 8 2/3 innings) are strong candidates for two of the three available bullpen jobs. Connor Brogdon (4.15 ERA, 8 2/3 innings) is a candidate. He allowed two runs in one inning Saturday. Brogdon is out of options, which is a consideration as the Phillies finalize the roster.

José Ruiz (0.90 ERA, 10 innings) threw another scoreless inning Saturday. Andrew Bellatti (5.87 ERA, 7 2/3 innings) allowed three runs while recording one out.

Neither Ruiz nor Bellatti is on the 40-man roster.

Harper is ready to roll
Bryce Harper said he is healthy after going 0-for-2 with one RBI in his first Grapefruit League game since March 14. He had been sidelined because of soreness in his lower back. He will be ready for Opening Day.

Will Rojas make the team?
Johan Rojas beat out a potential double-play grounder in the second to drive in a run. He reached on an infield single in the fourth. He then stole second, reached third on an error and scored. Rojas is batting .176 with a .467 OPS this spring, but he has four hits in his past 16 at-bats (.250) with one walk and one strikeout.

Rojas has not been told if he has made the Opening Day roster. If he does not, Cristian Pache and Jake Cave could both make it.

“We have to do the right thing by him, which is making sure that we don’t bury him offensively at the big league level and then have to send him out,” Thomson said about Rojas. “We’ve got to be very, very sure that he’s going to perform, just keep his head above water, really.”