HAMBURG, Germany — Paul Casey of England defied windy and rainy conditions to shoot a 6-under 66 Thursday and take a one-stroke lead after the opening round of the European Open.

The four-time Ryder Cup player, who said he has been struggling for several days with a sore throat, started late and had to deal with increasing winds in the afternoon but still carded seven birdies and a bogey at the Green Eagle Golf Course.

Casey finished a shot clear of Austria's Matthias Schwab, who had an eagle on the par-5 15th hole, then a bogey on the 17th before finishing with his fourth birdie.

Scottish rookie Robert MacIntyre, home favorite Max Rottluff and England's Ben Stow are two shots off the pace.

Sweden's Alexander Bjork, Australia's Lucas Herbert and English player Ben Evans were at 3 under, just ahead of a group of four including 2016 Ryder Cup star Thomas Pieters.

Xander Schauffele finished at 1 over after three bogeys in his opening nine, then a double-bogey on the par-4 10th, before the American picked up five birdies and a bogey in his last seven holes.

Defending champion Richard McEvoy was at 5 over.