Harchibald took advantage of a fall at the final flight to make a winning return to action in the John James McManus Memorial Hurdle at Tipperary.
Paul Carberry's mount, runner-up in the Champion Hurdle, looked held by the long-time leader, who was two lengths up going to the last, but Solerina overjumped and gave David Casey no chance of staying in the saddle.
That left Harchibald, trained by Noel Meade, to come home unchallenged from Ansar. Both Solerina and Casey appeared none the worse for the tumble.
Meade conceded his charge had been a fortunate winner.
He said: "You need a bit of luck some days. I thought he would need the race and although it is a fabulous prize, it is a pity it is not a fortnight later, it comes a bit early in season.
"The horse is 14 kilos heavier than his best racing weight. He was a little bit fitter last year for this race, but this year we are trying to mind him for later in the season.
"The ground was deep enough down the back straight. He will go where the ground is good. I don't want to run him on heavy ground."
Possible targets for the six-year-old include the Morgiana Hurdle at Punchestown and the Fighting Fifth at Newcastle.
Solerina's owner John Bowe said: "You only realise how precious she is when something like this happens.
"David gave her a lovely ride, she just went long coming down to the last, landed on her off-fore and tripped over. She would have won.
"She's tough and game as ever. There's not a scratch on her, but we'll see how she is in the morning.
"She may go for the Irish Cesarewitch depending on how she is, otherwise we might wait for the November Handicap or the Lismullen Hurdle."