The Republic of Ireland's World Cup 2022 qualifying campaign began in disappointing fashion as they fell to a 3-2 defeat by Serbia in Belgrade.

Alan Browne finished a well-worked Republic move to head the visitors into an 18th-minute lead.

Dusan Vlahovic levelled for the hosts after 40 minutes before substitute Aleksandar Mitrovic turned the game on its head with a well-executed lob.

Mitrovic's header put Serbia two up before James Collins' late consolation.

Serbia captain Dusan Tadic was outstanding, setting up all three of his side's goals.

With Portugal widely expected to top the group, the result is a blow for the Republic, who are hoping to contend with Serbia for a play-off spot.

The result extends Republic boss Stephen Kenny's wait for a first win since taking charge to nine games, although there were clear signs of improvement from the performances they produced during the three international windows in the latter months of 2020.

The Republic started brightly with plenty of crisp passing sequences and were rewarded with their first goal from open play under Kenny as Browne headed the visitors into the lead with the kind of cohesive, clinical attacking thrust that was largely absent during Kenny's first eight games in charge.

Browne started the move by feeding Enda Stevens down the left before bursting into the box.

Stevens found Callum Robinson, who drove past Stefan Mitrovic and clipped his cross into Browne where the Preston midfielder directed his downward header back across scrambling Serbian stopper Marko Dmitrovic and into the corner for the Republic's first goal in 678 minutes.

The Irish defended stoutly for much of the first half, but were undone five minutes before the interval when Vlahovic levelled for the hosts, the Fiorentina frontman latching on to Dusan Tadic's flick-on header before finding the bottom corner with an expertly placed left-footed strike.

Tadic and Mitrovic combine to break Irish hearts

With cracks appearing in the Irish defence, Serbian skipper Tadic grew increasingly influential, teeing up Filip Djuricic three minutes after the equaliser only for the Sassuolo forward to send a weak shot wide.

Tadic then tried unsuccessfully to catch Republic goalkeeper Mark Travers out with a shot direct from a corner as the visitors just about survived a sustained spell of pressure at the end of the half.

The Republic did not have as much joy in the attacking third after the break, but they felt they should have been awarded a penalty when Aaron Connolly went down under Stefan Mitrovic's challenge.

The hosts had their own appeal waved away, however, four minutes later when Vlahovic fell over Coleman as the Irish skipper lost his footing, with Italian referee Davide Massa again unmoved.

Tadic continued to find space and punished the away side when the in-form Ajax attacker fed Mitrovic, who lobbed Travers with aplomb to fire Serbia ahead.

Tadic was the architect once more as the Serbs put the result beyond the Republic, the former Southampton playmaker standing up a cross for Mitrovic, who judged his header to perfection.

The Republic were offered a lifeline by substitute Collins, who profited from a defensive error from the hosts, but the Irish were unable to rescue a point as they did when the sides met in Belgrade in 2016.

Kenny's bold selection doesn't pay off

Kenny's line-up undoubtedly had a bold and inexperienced look to it as the Republic boss switched to a back five.

Shane Duffy, who has struggled at Celtic this season, dropped out of defence with West Brom's Dara O'Shea preferred alongside Ciaran Clark and returning captain Seamus Coleman, who earned his first cap under Kenny.

There were also starts in midfield for Jayson Molumby and Josh Cullen, winning their sixth and fifth caps respectively, as Jeff Hendrick settled for a place on the bench.

Browne joined Preston team-mate Molumby in a midfield that lacked experience but promised energy and mobility in abundance, with Aaron Connolly and Callum Robinson entrusted to lead the attack.

While an extensive list of injured absentees factored into Kenny's thinking, O'Shea was the only survivor from the Republic's last game, a 0-0 Nations League draw against Bulgaria in November, while only Stevens and Robinson started the Euro play-off defeat by Slovakia a month earlier.

Kenny can be buoyed by his side's first-half display. While Serbia's equaliser could have been easily avoided, the Republic's three centre-backs worked tirelessly to suppress their hosts while O'Shea demonstrated his ability to play line-breaking passes from the back.

The second period was considerably more disconcerting, however, as the Republic's energy levels faded, allowing Tadic to twice fashion openings for the deadly Mitrovic.

Kenny and the Republic will look to regroup ahead of Saturday's home qualifier against Luxembourg, while Serbia host Portugal, who beat Azerbaijan 1-0 in their opener.