Dedryck Boyata made his first appearance for Celtic since April in their 2-0 friendly loss to Inter Milan.
The Belgium defender played 45 minutes of the International Champions Cup match in Limerick as manager Brendan Rodgers named an experimental line-up.
Boyata, 25, had been out since being injured in the Scottish Cup semi-final defeat by Rangers last season.
Eder headed Inter's first before Antonio Candreva's sublime chip over Leo Fasan made it two.
Nadir Ciftci had Celtic's best chance at Thomond Park when he volleyed off the crossbar, while Ryan Christie was threatening on a number of occasions.
Boyata's return is a boost to manager Brendan Rodgers ahead of Wednesday's Champions League play-off first leg against Hapoel Beer Sheva at Celtic Park.
Fellow defenders Erik Sviatchenko and Jozo Simunovic are likely to be missing.
The match in Limerick was former Rangers defender Frank De Boer's first game in charge of Inter.
Dutchman De Boer took over from former Manchester City boss Roberto Mancini earlier this week.