"Yeah, the exam that he went through, the images taken in Denver concur with what's been found in the exam in Boston and he does have a compression fracture," said Farrell. "That means it's non-displaced. But at the same time, we feel like he'll return this year. He's in a boot right now, will be for the time being. We feel like he'll be back to us before this year is out. We're hopeful in the regular season, yes."
Red Sox second baseman Dustin Pedroia fractured his navicular bone on June 25, 2010, and played just two games the rest of that season. However, that break was much more severe.
Ellsbury initially was injured on Aug. 28, when he fouled a ball off the foot, and he played for more than a week before being shut down on Saturday. He aggravated the injury while stealing second base in the 10th inning of Thursday's game against the Yankees. He came around to score the go-ahead run in Boston's 9-8 victory.
"I've talked to him about it," Pedroia said. "Mine was a little a different, but same area. It's something you can't mess with. Got to make sure you take care of it and you're able to play and run and not be sore the next day."
The Red Sox, who lead the Rays by 7 1/2 games in the American League East, have already proven they can withstand an injury to a key player.
Clay Buchholz, who will return on Tuesday night against Tampa Bay, last pitched for Boston on June 8.
"We'll have to pick up the slack," said Pedroia. "He's a huge part of our lineup and team. Guys are going to have to step up, and they will."
Jackie Bradley Jr., who was recalled from Triple-A Pawtucket on Saturday, will get some playing time in center while Ellsbury is out. Shane Victorino, Boston's starting right fielder, can also play center.
The leadoff spot will probably be occupied mainly by Victorino, but also at times by Daniel Nava.
"Obviously it's big," said Jon Lester. "He's a big part of this team. Hopefully he's a quick healer and he'll be back soon for us."
Farrell didn't have a precise timetable for when Ellsbury will return.
"Not at this point," Farrell said. "The only thing we do have is that he'll be in a boot for five days. After that, we'll see how he responds to treatment and how he's feeling himself."