TOKYO -- Los Angeles Dodgers shortstop Mookie Betts is still struggling to recover from an illness, with manager Dave Roberts pessimistic that the eight-time All-Star will be ready for Opening Day against the Chicago Cubs on Tuesday in Japan.

Betts was able to go through a light workout Sunday but became tired quickly.

"Really showed some fatigue, understandably so," Roberts said. "We'll see how he comes in tomorrow. He should be here for the workout. We'll try to do a little more tomorrow."

Roberts said Saturday that Betts started suffering from flu-like symptoms in Arizona, the day before the team left for Japan. He still made the long plane trip but hasn't recovered as quickly as hoped and missed the Dodgers' two exhibition games against Japanese teams over the weekend.

Roberts said Betts will need to show substantial improvement Monday to play against the Cubs.

"To be able to go through an entire workout and not feel that same fatigue would give us a chance," Roberts said. "But anything outside of that, I just don't think our training staff would feel good about that."

Betts hasn't taken live at-bats in nearly a week.

"We're really trying to be mindful of not just Opening Day," Roberts said. "Not putting him in harm's way. ... We don't want to put him in position where he could get hurt."

Betts is making a full-time transition to shortstop this season after playing most of his career in right field and second base. The 2018 American League MVP hit .289 with 19 homers and 75 RBIs last season, helping the Dodgers win the World Series.