Stan Wawrinka failed to convert 12 break points as he lost to Sam Querrey in the second round of the Fever-Tree Championships at Queen's.
The Swiss, who has dropped to 261st in the world after injury, was beaten 7-5 6-7 (3-7) 6-1 by the American.
Wawrinka, a three-time Grand Slam champion, wasted seven set points at 5-4 in the first set and only capitalised on one of 13 break points in the match.
Querrey dominated on serve, hitting 25 aces as he closed out victory.
Fifth seed Querrey will face the winner of Wednesday's match between Croatian sixth seed Marin Cilic and Luxembourg's Gilles Muller.