Republic of Ireland lost ground on FIFA World Cup qualifying rival Serbia after it was held to a 1-1 draw by Georgia in Tbilisi.

Shane Duffy scored after just four minutes to delight the travelling Ireland supporters, who had seen their side take 12 points from its opening six Group D matches.

But Georgia dominated possession and took control of the game before Valeri Qazaishvili equalised after 34 minutes with a goal that seemed to knock the stuffing out of Ireland.

Duffy went close to restoring Ireland's lead on the cusp of half-time, but the visitors' performance thereafter was poor, with stray passes and a lack of bite in midfield allowing Georgia an easy ride as it picked up the fourth draw of its campaign.

Meanwhile, Serbia's 3-0 win over Moldova ensured t went two points clear of Ireland ahead of the two sides meeting in Dublin on Wednesday (AEST), when Martin O'Neill's men go in search of a victory to revive their hopes of winning the group.

Ireland made the breakthrough in just the fourth minute. Cyrus Christie's long, looping free-kick found the head of Duffy, who rose above on-rushing goalkeeper Giorgi Makaridze to nod the ball into the empty net.

Georgia dictated possession without threatening an equaliser and it was Ireland that looked more likely to grab the game's second goal when Jonathan Walters, earning his 50th cap for his country, whipped over a cross that James McClean sent just wide of the left post with a glancing header.

Shane Long then rattled a well-struck shot over the crossbar from 25 yards but, just as Ireland were starting to look comfortable, the hosts drew level.

Valerian Gvilia's low pass found Jano Ananidze, who side-stepped the challenge of Christie before playing in Qazaishvili to finish with a low shot through Darren Randolph's legs.

Makaridze ensured the scores stayed level at the break with a brilliant reflex save just before half-time when Duffy met Robbie Brady's corner with a far-post header.

Ananidze drilled a low, right-footed shot just wide of Randolph's net four minutes after the re-start, while Harry Arter's lobbed attempt after an hour was all Ireland mustered in a subdued opening to the second half.

Ireland's energy and poise waned as the second half went on, although it showed a glimpse of the free-flowing football it is capable of when a break down the right flank saw Christie tee up Long for a header that was not far wide of the target.

Walters also hit a rising drive that stung the palms of Makaridze, but Ireland's push for a late winner lacked conviction and O'Neill will hope his side are in better form in Wednesday's (AEST) crunch match at Aviva Stadium.