Rory McIlroy trimmed Patrick Reed's lead to two shots as the final round of the Masters Tournament got under way on Sunday.
The American entered the day with a three-shot advantage and anticipation was high for the final pairing after their sensational singles duel at the 2016 Ryder Cup - which Reed won one up.
McIlroy was chasing the career grand slam at Augusta National and he made two birdies in his first four holes but also had a bogey to sit at 12 under, with Reed level par for the day.
Jon Rahm and Rickie Fowler were then nine under, a shot clear of Henrik Stenson and Jordan Spieth.
The leading pair showed signs of nerves off the first tee, with Reed sending his tee-shot left and having his follow-through impacted by a tree, while McIlroy went a long way right, but both ended up in the front-left bunker with their second.
Reed's shot from the sand found the very back of the green for a bogey and with McIlroy getting up and down, the lead was quickly down to two.
The Northern Irishman then produced a moment of sheer brilliance on the second, hitting his second from 197 yards to four feet and two-putting for a birdie, with Reed getting up and down from the sand for a par.
The lead was back to three on the next, however, as McIlroy dropped a shot after leaving his second short of the green and Reed made a birdie putt from the back fringe.
Four-time Major winner McIlroy hit straight back, with a tee-shot to three feet on the fourth giving him a birdie.
Rahm took advantage of the second with two putts from 48 feet and put his approach to the short third to five feet to get to double figures. A bogey on the fourth then dropped him back alongside Fowler, who started with four pars.
Some dialled-in iron play brought Spieth birdies on the first and fifth, sandwiching another gain on the second.
Stenson hit an approach to ten feet on the first for his only birdie of the day so far.
Paul Casey played on Saturday with marker Jeff Knox but he was in the top ten and chasing down the course record on Saturday.
He made birdies on the second, fifth, eighth, 11th and 12th before he followed an eagle on the 13th with another gain on the next.
Justin Rose, Bubba Watson and Justin Thomas were also six under.
Webb Simpson had stolen the early headlines as he made back-to-back eagles on the seventh and eighth.
On the par four he hit an approach from 166 yards which pitched left of the flag and rolled down the slope, before his chip on the eighth took two bounces, hit the pin and dropped in the hole.