Novak Djokovic needed 10 match points to claim a hard-fought straight-sets victory over the dangerous Borna Coric on Wednesday, setting up a Monte Carlo Masters third-round clash with Dominic Thiem.
The 12-time Grand Slam champion, playing only his fourth tournament since Wimbledon last July after struggling with a right elbow injury, overcame some late nerves to win 7-6 (7/2), 7-5.
Djokovic is working with long-time former coach Marian Vajda for the first time in almost a year after splitting from Andre Agassi, and the 30-year-old has looked rejuvenated in Monaco after early exits in Indian Wells and Miami.
The Serbian will next face Austrian fifth seed Thiem with a possible quarter-final against defending champion Rafael Nadal, who plays Aljaz Bedene later on Wednesday, up for grabs.
The first game set the tone for the rest of the match, with Djokovic eventually holding after nine minutes of bruising baseline rallies that included a missed break point for Coric.
The 21-year-old Croatian also saved a break point in his first service game, but could not fend off Djokovic for long as the two-time Monte Carlo winner moved 3-1 ahead when Coric mishit a smash.
Coric has been in fine form so far this year, reaching the semi-finals at Indian Wells before a run to the last eight in Miami.
And he dug deep to break back thanks to two backhand unforced errors from Djokovic.
But Djokovic was rock solid in a tie-break as Coric became ragged, dumping a simple short ball into the net and firing a backhand long to gift his opponent the first set.
Djokovic was showing the ferocity and accuracy of old in his groundstrokes and he had the better of three straight breaks to take control.
But the 39th-ranked Coric saved two match points on his own serve, before fighting back from 40-0 down as Djokovic struggled to get over the line as he served for the match.
A succession of wild backhands and a tame forehand into the net saw four more match points come and go, before Coric levelled the set at 5-5 as Djokovic blasted wide and long.
He rediscovered his composure, though, to break again and finally complete the job at the 10th time of asking as Coric sent a backhand flying long.
The former world number four, who has struggled over the last year with a right wrist injury, followed up his first-round victory against Tomas Berdych with a solid display on centre court.