OWINGS MILLS, Md. -- It's uncertain whether the Baltimore Ravens will have cornerback Jimmy Smith at the start of the 2018 season.

Smith, the team's top cornerback, tore his left Achilles on Dec. 3 and missed the last four games. With the normal recovery being six to eight months, it will be close as to whether Smith will be fully recovered for the beginning of next season.

"It's up in the air," coach John Harbaugh said Tuesday. "If you do the math, eight months will be September for Jimmy. That's conservative. That's really a little more than that. We'll see where he's at."

Smith was having the best season of his seven-year career, making three interceptions, breaking up nine passes and returning a fumble 47 yards for a touchdown. He was ranked as the No. 14 cornerback in the NFL this season, according to Pro Football Focus.

On Monday, Smith was in the locker room with a cast on his left foot. He was able to return to the facility after serving a four-game suspension -- which coincided with his time out with the injury -- for performance-enhancing drugs.

What helps Baltimore is cornerback is among the team's deepest positions. The Ravens return Marlon Humphrey, Brandon Carr and Maurice Canady and get back Tavon Young from a season-ending ACL tear.

Without Smith, Baltimore allowed the second-most passing yards in the NFL, giving up an average of 259.5 yards over the last four games. Only the Carolina Panthers gave up more (289.3).

"I'm hopeful," Harbaugh said of Smith's return. "But we're going to have a bunch of corners here too, to make sure we have enough corners."

Elsewhere, Pro Bowl guard Marshal Yanda isn't going to be rushed back after breaking his ankle in Week 2. The Ravens won't see him on the field for full-team drills until training camp in late July.

"But Marshal will be ready to go long before that," Harbaugh said.