Jonathan Papelbon pitched in the first three games of the series and has gone two innings in each of the past two outings.
He threw 31 pitches in Sunday night's 12-inning, 5-4 loss to the Angels. As usual, the righty was magnificent, keeping the Halos off the scoreboard while striking out three.
Can he pitch again on Monday?
When told that pitching coach John Farrell labeled him a question mark, Papelbon gave a cryptic response when asked of his status.
"Question mark," Papelbon said. "I'm saying that's a question mark from me, too. But I feel fine. I'll wake up in the morning and see how I feel."
In 12 career postseason appearances, Papelbon has allowed no earned runs. If Papelbon is able to pitch Monday and record two outs, he will break a postseason record. Joe Niekro has the current record for most career postseason innings (20) without allowing a run. Papelbon is at 19 2/3.
"I don't know, I just seem to kind of try to lock in better [in October]," Papelbon said.
If he can't go on Monday, his 'mates in the bullpen will do their best to step up. The bulk of the responsibility is likely to fall on Manny Delcarmen, Justin Masterson and Hideki Okajima.
"Once you get that call, you have to be ready," Delcarmen said. "Pap threw two innings today, so he might be down tomorrow, we don't know yet."
The Red Sox might also be without hobbled third baseman Mike Lowell, who is playing with a partial tear of the labrum in his right hip. Lowell is 0-for-8 in the series.
Will he be able to play on back-to-back days?
"I don't know; we'll see," said Lowell. "A lot hinges on [Monday]."
Lowell continues to earn admiration for playing through an injury that would be too painful for a lot of players.
"It shows the heart that he has for this team, just going out there and putting everything on the line," said Delcarmen.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.