For Spieth, that was as welcome as being an Open contender once again.
"It feels inside the ropes, from the first tee forward, the most normal of any tournament we have played thus far relative to that same tournament in previous years," Spieth said.
His 5-under 65 certainly turned back time to four years ago when he lifted the claret jug at Royal Birkdale — the last English venue to host the British Open — when he was hitting the ball better than he ever has.
Spieth was a shot off the lead held by Oosthuizen, who saved par from a fairway bunker on No. 18 for a 6-under 64. That tied the lowest opening round at Royal St. George’s, previously set by Christy O’Connor Jr. in 1981.