Sources: Tampa Bay Buccaneers' Leonard Fournette likely out for rest of regular season; team signing Le'Veon Bell

Tampa Bay Buccaneers running back Leonard Fournette is "likely" to be placed on injured reserve because of the hamstring injury that left him on crutches Sunday night, a league source told ESPN's Adam Schefter on Tuesday.

Fournette would miss the rest of the regular season, but a source said he is expected to return for the playoffs.

With Fournette sidelined, the Buccaneers have signed Le'Veon Bell to back up Ronald Jones, the team announced Wednesday.

Fournette suffered the injury in the third quarter of Sunday's 9-0 loss to the visiting New Orleans Saints.

Last week, the Bucs placed veteran running back Giovani Bernard, their third-down back, on injured reserve after he suffered an MCL sprain to his knee and a stretched tendon in his hip. A source told ESPN that Bernard "could be back in time for the playoffs."

But without Fournette and Bernard, the Bucs had Jones, who had been unseated in his starting role by Fournette last year, and second-year running back Ke'Shawn Vaughn. Pass-catching has not been Jones' forte, and Vaughn lacks experience.

In Fournette's absence, the Bucs were limited in their short passing game at running back against the Saints. Jones rushed for 63 yards on eight carries and caught two passes for 8 yards. Vaughn had 19 rushing yards on three carries.

Bell, 29, a former All-Pro, last played for the Baltimore Ravens, with whom he rushed for 83 yards on 31 carries and two touchdowns and caught one pass on two targets in five games.

Bucs inside linebacker and longtime captain Lavonte David, who left Sunday's game late in the fourth quarter and did not return, was diagnosed with a foot sprain, a source told ESPN. The source said it's possible David could be back for the final regular-season game against the Carolina Panthers but that his recovery time could take as long as four weeks.

ESPN's Jeremy Fowler contributed to this report.