Christian Eriksen's first goal for Inter helped Antonio Conte's men earn a battling 2-0 away win against Ludogorets in the opening leg of their Europa League last-32 tie.
The Serie A side were not at their best at Ludogorets Arena on Thursday but scored the opener from the best move of the match, Eriksen curling home from the edge of the box.
January signing Eriksen hit the crossbar from distance and Romelu Lukaku's late penalty confirmed a victory for the Nerazzurri that saw them bounce back from successive domestic defeats.
Inter, who began with Lukaku on the bench, struggled to impose themselves in the opening exchanges but Ludogorets goalkeeper Plamen Iliev had to make a smart stop to keep out Cristiano Biraghi's volley in the 25th minute.
The upright kept out Alexis Sanchez's clever flick after the restart, then Lautaro Martinez lashed a long-range strike narrowly over the crossbar as Inter increased the tempo.
Iliev made another fine save to turn away Eriksen's bouncing 20-yard volley, but the goalkeeper could do nothing about Inter's first goal in the 71st minute.
Sanchez and substitute Lukaku were involved in patient passing in the build-up, with Eriksen sweeping an excellent finish out of Iliev's reach.
It was almost 2-0 moments later as Eriksen's thumping drive beat Iliev but not the woodwork, Lukaku's arrival having given Ludogorets more to think about in defence.
Ludogorets, who were without their star striker Claudiu Keseru due to injury, failed to record a shot on target and face an uphill battle at San Siro next week after Lukaku converted from 12 yards in added time following Anicet Andrianantenaina's handball.
What does it mean? Inter get the job done
After consecutive defeats in the Coppa Italia and in Serie A to Napoli and Lazio respectively, Inter again found it difficult to produce their best football but they ground out a much-needed win. It is doubtful whether Conte values Europa League success over the Scudetto, though.
Iliev unlucky to miss out on clean sheet
Ludogorets had their backs against the wall for much of the game and relied on goalkeeper Iliev to keep them in the tie. He made a handful of excellent stops in a superb individual showing.
Martinez unable to justify Messi praise
Labelled "spectacular" by Argentina team-mate Lionel Messi in the build-up to the game, reported Barcelona target Martinez made very little impact before he was replaced by regular strike partner Lukaku.
Ahead of next week's second leg, Inter host Sampdoria on Sunday while Bulgarian league leaders Ludogorets are away to Etar on the same day.