Four-time champions Leinster sputtered at Leicester on Friday night before pulling ahead in the dying minutes to open round two of the Champions Cup group stage with a 23-15 win in pool 3.
Leinster had opened the competition at home by crushing Londoners Harlequins, while Leicester were overpowered at La Rochelle.
The Irish province dominated territory from the start, but made repeated handling errors in the face of a tigerish home defence.
Leinster's carelessness with the ball also presented the home team with the only two tries of the first half.
Adam Radwan pounced on a Leinster drop after 20 minutes to hare away, dribbling the ball before diving to touch down.
The other Leicester winger, Ollie Hassell-Collins, also showed his footballing skills, chasing his own kick ahead and pouncing when the Leinster defence could not gather the ball.
Harry Byrne kicked two first-half penalties for the visitors to one by Billy Searle for the hosts.
Searle also missed a conversion and, with Leicester 15-6 ahead, then missed an early penalty in the second half.
Ireland scrum-half Jamison Gibson-Park responded by scampering through some ineffective tackles to score. Byrne converted to close the gap to one point.
Leinster pressed, and Byrne kicked a 60th-minute penalty to put them ahead by a point.
With eight minutes left, Ireland hooker Dan Sheehan, a second-half replacement, crashed over after a lineout and Ireland fly-half Sam Prendergast, who had come on in the 61st minute, converted to seal the win.