The seven-time Grand Slam champion has hit top form in New York after nearly five months out with a right wrist injury and extended his major match-winning streak to 18 with a stunning display of shotmaking against a fellow big-hitter.
Alcaraz's serve came under pressure in the third game when Paul fired an exquisite 100 mph forehand winner around the net that brought Arthur Ashe Stadium to its feet, but the Spaniard stood firm before striking late to snatch the opening set.
The 23-year-old left a vapour trail with a cross-court winner to carve out an early opening in the second set and swiftly took a 2-0 lead, before trading breaks with Paul and breezing through the remaining games for a commanding lead.
Even with much of the showcourt crowd yearning for a home winner, second seed Alcaraz continued to steal the show with his audacious play and moved to the brink of improving his win-loss record against American players at the Grand Slams to 13-0.
After shifting down to cruise mode, Alcaraz briefly flinched at the finish line but he regrouped to deliver the knockout blow and set up a meeting with American Ben Shelton or Greek Stefanos Tsitsipas in the next round.
