Frank de Boer's Inter bow produced a 2-0 International Champions Cup win over a severely weakened Celtic side in Limerick on Saturday, with Antonio Candreva's stunning late effort adding to an Eder header.
The Scottish champions attracted significant criticism for cancelling a Scottish Premiership match against Partick Thistle in order to face Inter and ultimately slumped to defeat in De Boer's first match since replacing Roberto Mancini on Tuesday.
Despite fielding a team including few regulars, Brendan Rodgers' men gave a good account of themselves, but an Eder header just before the break and an exquisite Candreva chip settled things in Inter's favour.
Poor play in midfield from Celtic almost gifted Inter an opening goal in only the third minute, but Ever Banega was brilliantly denied by Leo Fasan from 20 yards after collecting Ivan Perisic's cut-back.
The significantly under-strength Celtic side managed to ease the pressure being exerted by Inter during the opening 20 minutes and eventually crafted a great chance with half an hour played - Stuart Armstrong forcing Samir Handanovic into a fine save after a clever one-two with Nadir Ciftci.
Inter generally looked the more likely to make a breakthrough, though, and eventually broke the deadlock on the stroke of half-time - Eder nodding in from close range.
Inter remained in the ascendancy after the break, but Celtic nearly drew level in the 59th minute, only for the crossbar to deny Ciftci, whose fine 25-yard volley had Handanovic beaten.
The Italian side wrapped things up with 19 minutes to go, though, as Candreva latched on to a throughball and lobbed Fasan with a sublime chip on the edge of the area.