Jannik Sinner returned to top spot in the world for the first time since early November after a 7-6 (7-5) 6-3 Monte Carlo Masters final victory over defending champion and world number one Carlos Alcaraz.
The Monaco decider was the first meeting of the top two in the world since Sinner won in straight sets in the final of the ATP Championship last November.
In a tense and tight match with plenty of big shots, both players struggled with the windy conditions, which added an element of unpredictability to proceedings and led to 83 unforced errors between the pair.
The win gives the 24-year-old Italian his third Masters 1000 title of the year having already triumphed at Indian Wells and Miami, and extends his winning run in Masters series events to 22 matches.
After exchanging early breaks, neither player was really able to impose themselves on the match with both having to work hard at times to hold serve.
However, in the tie-break, Sinner upped his first serves and after squandering the first of two set points, an Alcaraz double fault gave him the initiative in the match.
Sinner started the second set sluggishly and had to come from 15-40 down in his opening service game before Alcaraz broke to go 2-1 ahead and hold for 3-1.
But the Italian managed to stay in the match as Alcaraz failed to dominate his service games, taking a 4-3 lead to put the pressure on his 22-year-old opponent, who had won 10 of their 16 previous encounters.
Another shaky service game from the Spaniard gave Sinner another break point, and from there he made no mistake, quickly wrapping up his 27th ATP Tour victory.