Grand Slam-chasing Ireland avoided a major upset to keep themselves on course for Guinness Six Nations glory with a disjointed 34-20 bonus-point win over Italy.

Andy Farrell’s depleted side were well below their fluent best in Rome but ultimately claimed victory thanks to two Mack Hansen tries following scores from James Ryan, Hugo Keenan and Bundee Aki.

Fearless Italy had the world’s number one side rattled for large parts of a relentless encounter at Stadio Olimpico.

Stephen Varney’s try, a superb breakaway score from Pierre Bruno and 10 points from Paolo Garbisi kept Kieran Crowley’s hosts in contention and they trailed by just four points with 15 minutes remaining.

But the Irish, helped by nine points from Ross Byrne, survived the scare to remain on course for a championship clean sweep moving on to March appointments with title rivals Scotland and England.

In-form Ireland arrived in the Italian capital seeking a third consecutive tournament success but without a host of star names due to injury.

Swathes of green jerseys packed the terraces and witnessed a side steered by rookie half-back pairing Byrne and Craig Casey make a blistering start.

James Lowe, who benefited from a favourable call to claim a try in the 32-19 win over France a fortnight ago, was denied a quick-fire score on this occasion as replays showed he dropped the ball just before grounding with a one-handed finish under pressure from Ange Capuozzo.

Yet Irish disappointment was swiftly tempered by stand-in skipper Ryan capitalising on a Lowe assist following a fine Aki offload to cross inside three minutes.

Bundee Aki was in the thick of the action for IrelandBundee Aki was in the thick of the action for Ireland (Steven Paston/PA)

Italy have not won at home in the championship since a shock 22-15 success over Declan Kidney’s Ireland a decade ago.

Sparked by the mercurial talents of fit-again fly-half Garbisi and rapid full-back Capuozzo, they contributed to a thrilling encounter and quickly hit back as Wales-born scrum-half Varney sneaked over following strong running from Lorenzo Cannone.

Ireland full-back Keenan then wriggled through a host of tackles to dive over before Aki, who was instrumental in his side’s opening two tries, burst clear to stretch the scoreboard midway through a breathless first half after a Garbisi penalty briefly reduced the deficit.

Following a temporary lull during which Casey recovered from being flattened by Italian lock Niccolo Cannone and prop Finlay Bealham departed injured, Farrell’s men had the bonus-point wrapped with only 35 minutes on the clock when Hansen dived over wide on the right at the end of sustained pressure to help subdue home support.

But the visitors had little time to enjoy the cushion as their advantage was halved to seven points with the final action of a gripping opening period.

Italy wing Bruno superbly intercepted Aki’s pass in his own half and darted around 70 metres to put the contest firmly back in the balance and ignite fresh optimism among Azzurri fans.

Another Garbisi penalty cut the lead to 24-20 and Farrell cut a concerned figure in the stands after Aki was denied a second score of the afternoon as replays showed he lost possession on the ground before regathering.

A Byrne penalty helped steady the nerves before Hansen slipped through the Italian defensive line nine minutes from time to ensure Ireland claimed a precious, albeit unconvincing, victory.