It all added up to a cool 96 minutes of confidence-building work for the 22-year-old phenom, who will next look forward to a battle with a North American foe as he mounts his bid to win a second major title, and first at Wimbledon.
The Italian won 36 of 42 first-serve points, and dropped just 15 points overall on serve. He saved the only break point he faced to improve to 12-3 lifetime at Wimbledon and 41-3 on the 2024 season.
Sinner will play the winner of the match between Canadian Denis Shapovalov and American Ben Shelton, the No 14 seed, next. That match was postponed due to rain and will be played on Saturday, first up on No.1 Court (at 1PM local time).
Earlier in the tournament, the 22-year-old Italian defeated German Yannick Hanfmann (6-3, 6-4, 3-6, 6-3) and edged out Matteo Berrettini (7-6 (3), 7-6 (4), 2-6, 7-6 (4)).
Kecmanovic, ranked No 52, edged out Indian Sumit Nagal (6-2, 3-6, 6-3, 6-4) and won against Dutchman Tallon Griekspoor, the No 27 seed (4-6, 7-6 (7), 1-6, 6-2, 6-3) in the previous rounds of The Championships.
London (Grand Slam), other third-round results (All England Lawn Tennis and Croquet Club, grass, GBP 50.000.000, most recent results first):