DUNEDIN, Fla. - On the list of things no Phillies fans want to see in the final days of spring training, watching a guy who might very well be the team's most popular player leave a game with an injury would rank fairly high.

But that's what happened yesterday afternoon in Dunedin.

Ken Giles, the 24-year-old reliever who provided must-see TV as a rookie last season with his triple-digit radar-gun fastball, came out after facing only one hitter during the eighth inning against the Blue Jays. Giles exited with tightness in the middle of his back, in the middle of an at-bat against Toronto infielder Steve Tolleson.

Afterward, Giles assured everyone that it was simply done for precautionary measures, and that he was "not at all" concerned about his readiness for Opening Day.

"It's just tightness," Giles said. "It's just stiff. It doesn't hurt. I'm able to move around and stuff like that, but I'm not really concerned about it."

Giles said that he's had the pain for "a few days," but that it escalated when he took the mound and got Ryan Goins to ground out for the first out of the bottom of the eighth inning.

"It kind of grabbed me," he said. "But, like I said before, it doesn't bother me moving around. I just feel a little tension there. It's kind of stiff."

Giles planned to ice his back when the Phillies returned to Clearwater late yesterday afternoon. Manager Ryne Sandberg said the righthander would be examined by the team's medical staff in Clearwater, too.

"I'm a little concerned with [this injury], a little concerned with that," Sandberg said. "It's hard to tell if that has to do with his lower velocity. I'm just waiting to see him get checked out, waiting to see what it is."

Giles, who regularly hit 100 mph with his fastball in 2014, has hovered in the 90s this month. Yesterday, Sandberg said it was up to 95 mph, "as high as he's been this spring."

Late-inning relievers, who feed off adrenaline, typically see a slight uptick in their velocity when they jump from the exhibition season to the regular season. Giles was unconcerned with where he is with his fastball entering April.

"For me, I think that's perfect, where I need to be," Giles said. "I don't want to be too in shape when I go in the season, then, when the season goes on, I kind of wear down. So around where I'm at right now, I think it's going to be perfect. Then I can just continue to build up during the season."

The Phillies are likely to proceed with caution. If Giles' back continues to be an issue in the coming days, he could easily begin the season on the disabled list.

There is no reason to rush Giles back if he's not 100 percent healthy, especially not at the beginning of a 162-game season. It might be the course of action the team follows regardless of how Giles feels today.

But Giles didn't seem as if he'd have to convince management of his health, either.

"No, I don't think they'll be too pushy on that, because they know I'll speak the truth," Giles said. "Every day, they always want to know how I'm feeling and stuff like that, but I'm not really concerned about that kind of stuff."

Giles has a 6.23 ERA in nine appearances this spring; he's struck out 10 while walking seven batters in 8 2/3 innings.

Slowey released

Righthander Kevin Slowey was released in the morning, bringing more uncertainty to the vacant fifth starter's spot.

Slowey, 30, a veteran of seven big-league seasons, gave up six runs in two innings in a 18-4 loss to the Pirates on Monday. He had a 6.94 ERA in seven games (11 2/3 innings) this spring.

The Phillies can go in three directions for a fifth starter, which they don't need until April 12: They can acquire a player from another team; they can plug in a reliever such as Jeanmar Gomez for a spot start; or they can call on someone in minor league camp, such as Sean O'Sullivan or Joely Rodriguez.

O'Sullivan was called up to start yesterday's game against the powerful Toronto lineup. He gave up four runs on five hits, including home runs to Edwin Encarnacion and Sean O'Sullivan, in four innings.

"I kind of know what we have in O'Sullivan," Sandberg said. "In some regards, he hung in there after the home run. But, he'll throw strikes for us, and he'll change speeds. I pretty much know what we have in him."

O'Sullivan, 27, went 0-1 with a 6.39 ERA in three games with the Phillies last season.

Walk this way

Rule 5 pick Andy Oliver walked three of the six batters he faced in the seventh inning.

Oliver, who hadn't issued a walk in his first six spring appearances, has walked seven batters in his last three games. The lefthander is competing with Jeanmar Gomez, Phillippe Aumont and Cesar Jimenez for the final two spots in the Phillies' bullpen.

Luis Garcia, who didn't allow a run this spring until yesterday, is likely a lock, along with Giles, Jake Diekman, Justin De Fratus and closer Jonathan Papelbon.

On Twitter: @ryanlawrence21

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