Dodgers legend Tommy Lasorda is "doing well" after after undergoing heart surgery Thursday to replace his pacemaker ... and is expected to return to Dodgers Stadium soon. 

The 89-year-old is still in the hospital recovering from the procedure. He's not expected to be released for a few more days, team officials say. 

Tommy's been hospitalized several times over the years -- but keeps fighting through his ailments to make appearances at Dodgers Stadium. 

In fact, he attended the tribute to Vin Scully earlier this month.

Get well soon.