Diplomat got followers of Dermot Weld and Ruby Walsh off to the perfect start at Galway as the odds-on favourite recorded a comfortable success in the Novice Hurdle, the opening event of the 2013 festival.
Sent off the 9-10 market leader, the four-year-old - who once beat current Champion Hurdle favourite Our Conor on the Flat - was produced with a double handful by Walsh on jumping the second-last.
Weld, who is in search of a 27th trainers' title at Galway, celebrated his 65th birthday with a training double.
A positive ride by Pat Smullen paid dividends as Mustajeeb made virtually all the running in the European Breeders Fund Maiden, giving Weld an astonishing 22nd victory in the seven-furlong event.
The once-raced Sheikh Hamdan-owned juvenile was the 11-8 joint-favourite in company with the Aidan O'Brien-trained Friendship and always looked like holding the upper hand, having his rivals off the bridle rounding the home turn.
"He's a progressive colt and I see him up to Group class," Weld said.