London Irish captain Bob Casey scored his first Test try on an afternoon of few highlights for Declan Kidney's Ireland side in Santa Clara, California.
The Grand Slam champions, missing a host of first-choice players due to the Lions tour and Leinster's Heineken Cup success, finished off their two-match tour of North America with an uninspiring victory over the USA Eagles.
Casey barged over off a 13th-minute lineout maul to hand Ireland an early lead, which they boosted to 13-0 in first-half injury-time when new centre Ian Whitten finished off a breakaway attack.
But the US, who included six debutants in their starting line-up, were very keen to impress new coach Eddie O'Sullivan and they proved sticky opponents for an off-the-boil Ireland.
A lot of their good work was undone by a very poor place-kicking display from their number 10 Mike Hercus, who missed four kickable penalties.
Referee Chris White awarded the tourists a penalty try, 13 minutes into the second half, to almost put the game beyond the Americans' reach.
But, inspired by replacement out-half Ata Malifa, they launched a spirited fightback. Malifa dropped a goal and then set up centre Roland Suniula for a converted try.
With the gap down to 20-10 and both sides tiring, Ireland needed a final score to secure their second tour win and they got it when replacement scrum-half Eoin Reddan freed up tour captain Rory Best for a muscular burst to the line.
More than 10,000 spectators packed into the Buck Shaw Stadium to watch the Eagles takes on Ireland for the first time since they met at Lansdowne Road in 2004, when current Lion Tommy Bowe marked his debut with a try in a 55-6 home win.
O'Sullivan, who was in charge of Ireland back then, is beginning afresh as Eagles coach now and he said he was ‘honoured’ to take on his native country, and his successor as Ireland coach Declan Kidney, in his first match at the helm.
Kidney's new-look squad had failed to fire in last weekend's 25-6 defeat of Canada and it was thought that with an extra week's training and the team largely unchanged - Mike Ross came in for Tom Court in the front row - they would muster a much better display.
The early signs were positive with Best marshalling an impressive lineout and Casey and Mick O'Driscoll pressuring the American set piece into errors, but Ireland were never able to build on that.
Ian Keatley missed an early penalty chance before O'Driscoll picked up a loose ball at an American ruck and almost put his Munster colleague Ian Dowling over for a try.
Off a subsequent penalty, Ireland engineered a lineout maul which the Eagles could not cope with and Casey emerged from under a pile of bodies after being shunted over the line.
Keatley missed the conversion but was able to fire a left-sided penalty through the posts on 24 minutes, as Ireland continue to struggle to put phases together.
Ireland were lacking accuracy around the pitch but so too were American hooker Chris Biller, who had a nightmare time in the lineout, and Hercus.
The former Sale Shark missed penalty efforts after 30, 34 and 35 minutes to let Ireland off the hook for some poor discipline.
The home side paid the price for a failure to find touch from Hercus late in the first half when Keatley spotted a mismatch in midfield and ghosted through the gap before Whitten took it on to dive over for his second try in as many games.
Keatley's missed conversion left it at 13-0 in Ireland's favour but the try gave the Irish some encouragement for the second period.
Still, it was the US who took the initiative on the restart. But that good work was undone when Hercus missed his fourth penalty chance and another powerful lineout maul, with Casey and Tony Buckley to the fore, handed Ireland a penalty try which Keatley converted.
The Irish management tried to inject some pace to their game, with Eoin Reddan and debutant Denis Hurley coming on, but O'Sullivan's side were beginning to show their potential.
A turnover and quick break through the middle from Suniula showed have led to a try. Malifa settled for a drop goal, amid groans from the crowd.
Even better followed when Malifa ran past replacement Court in midfield and looped a pass out for the supporting Suniula to skip past Darren Cave's last-ditch tackle and crash over the line.
However, the Leinster-bound Reddan then hit Malifa with a strong tackle, his pack duly supplied turnover ball and the scrum-half spun a quick pass out for Best to burrow his way over from close range.