The Red Sox may be romping toward a playoff berth but that doesn’t mean their postseason roster is set.

There’s one area of the team very much in flux and it’s the bullpen.

Right now the Sox only have four sure things as far as roster spots go — closer Koji Uehara left-hander Craig Breslow and right-handers Brandon Workman and Junichi Tazawa. That leaves no more than two or three spots up for grabs and virtually every other pitcher on the team in the running for them.

That makes games like last night’s against the Tampa Bay Rays important not just in the standings but for the pitchers trying to make a statement.

In a 4-3 loss to the Rays for instance the Sox used three relievers — left-hander Drake Britton right-hander Rubby De La Rosa and veteran lefty Matt Thornton.

Britton who has found himself buried on the depth chart after a string of shaky outings was the most impressive while De La Rosa — who is the longest of longshots to make the playoff roster anyway — took the loss.

“It’s great to have competition within” said pitching coach Juan Nieves.

Much of the decision-making process will be matchup-specific. If the Sox get the Rays or A’s in the postseason they’ll want an extra left-hander for all the lefties in those lineups. But if it’s the right-hand heavy Tigers maybe they’ll go the other way.

“I think we’re going to match up our bullpen according to who we play in the first round” Nieves said. “You always have a chance to rotate them (in later rounds).”

In the meantime the relievers will do what they can to stand out. Britton for instance overcame a one-out walk in the seventh to start a pretty 1-6-3 double play. He then retired James Loney to start the eighth before being lifted.

“I hadn’t pitched in a situation like that in a while” Britton said. “It was nice to get back in there and having walked the go-ahead run to be able to get that double play and turn that successfully.