With Mitch Haniger on the injured list and a struggling Jarred Kelenic sent back to the minors, the Seattle Mariners could use another bat.

They signed veteran Justin Upton over the weekend, but he'll need some time to prepare after having been idle since spring training.

The Mariners might get some assistance for Tuesday's game against the visiting Oakland Athletics in the form of 2020 American League Rookie of the Year Kyle Lewis.

The former Golden Spikes Award winner as the best player in college before being a first-round pick in 2016, Lewis was "in transit" to Seattle on Monday after completing a 20-day rehabilitation assignment at Triple-A Tacoma.

"We'll see how he's feeling and hopefully add him to our roster," Mariners manager Scott Servais said. "I am going glass half-full that he's going to be available (Tuesday); that's what I am going with."

Lewis hasn't played in the major leagues since suffering a torn meniscus in his right knee trying to make a catch on May 31 last season. It's the same knee in which he suffered a torn anterior cruciate ligament in 2016.

Lewis played in 10 games for Triple-A Tacoma, going 11-for-35 with three homers and 12 RBIs. He played in the outfield once but was used strictly as a designated hitter after that.

Servais has been rotating players through the designated hitter spot to give players a bit of a rest, but said Lewis likely will occupy that role going forward.

"He tried (the outfield) a little bit early in the rehab and he was having a hard time bouncing back," Servais said. "So the adjustment there was to get him going feeling comfortable (as the DH). That doesn't mean he won't get back in the outfield at some point this year, but for where we're at right now and his anxiousness to get back and be a contributor here, I thought it was best to try to get him to be able to fill the DH spot as quick as we could."

Servais said Lewis' return could provide a boost for the offense.

"Any time you can get a player back that can change the lineup and impact the game the way he can, it's a huge shot in the arm," Servais said. "He hasn't played in the big leagues in a while -- it has been almost a year -- so you don't know what you're going to get, but I hope he comes back smoking hot."

The A's, who have lost 13 consecutive games to the Mariners dating to last season, are scheduled to start right-hander James Kaprielian (0-2, 4.50 ERA), who is 1-0 with a 6.35 ERA in five career appearances against the Mariners, including two starts.

The Mariners plan to counter with rookie right-hander George Kirby (0-1, 3.60), who will be making his fourth career major league start.

The Mariners won the series opener 7-6 Monday night, as rookie Julio Rodriguez hit his first homer -- a three-run shot -- at T-Mobile Park.

"Impressive player, obviously very talented," A's manager Mark Kotsay said. "Looks like he has pretty good command in the batter's box right now. He's got some confidence."