The comedian and actress were in a box together Monday night at Busch Stadium in St. Louis, watching a Cardinals game. They were spotted by eagle-eyed fans, who got them on camera together at different points in the evening ... including in this video, obtained by TMZ.

No signs of PDA, but they were definitely sitting together ... and seemed interested in maintaining a relatively low profile. We're told Chris did an on-camera interview at one point, and LB stepped away so she wouldn't be seen in the shot.

Chris has been performing comedy shows there lately, and it seems Lake is along for the ride. They're both single, and relatively fresh off of long-term marriages in recent years.

It's been about 3 months since CR got smacked across the face by Will Smith, and by all accounts ... he's doing just fine. Not only has he continued to work, but he now seems to have a new lady friend (maybe).