They join Russell Henley atop a crowded leaderboard at Torrey Pines after the second-round co-leader saved par on 18 to complete an up-and-down round and sit at five under par for the tournament.
Oosthuizen finished with a flourish, draining a downhill putt for eagle on 18 to cap his one-under 70 as he continues the quest for his second major title 11 years after winning the Open Championship.
The unheralded Hughes, meanwhile, eagled the 13th and birdied the last for a 68 on the day. He is the first Canadian to hold at least a share of the lead after 54 holes of a major since Mike Weir at the 1999 US PGA Championship.
The 30-year-old missed the cut in his last five PGA Tour starts and has only one career victory, in the 2016 RSM Classic at Sea Island.
Shades of Tiger.@MacHughesGolf eagles to jump to solo second. pic.twitter.com/EllOEtLOYX
— PGA TOUR (@PGATOUR) June 19, 2021
Impressive as Hughes was, the round of the day belonged to Rory McIlroy (67), who also birdied the 18th to reach three under for the tournament exactly 10 years after he closed out his runaway U.S. Open win at Congressional.
Bryson DeChambeau (68) also lurks two back of the leaders after a bogey-free third round.
Jon Rahm (72) is among the group at two under as he seeks his first major title, along with 2020 U.S. Open runner-up Matthew Wolff (73) and Scottie Scheffler (70).
The 2016 U.S. Open champion Dustin Johnson (68) is four back of the lead at one under along with 2020 US PGA champion Collin Morikawa (70), Christiaan Bezuidenhout (70), Xander Schauffele (72) and Kevin Streelman (72).
Among other notables, Brooks Koepka and Justin Thomas are at even par after shooting 71 Saturday, while Jordan Spieth (68), Martin Kaymer (69), Lee Westwood (71) sit one over.
Richard Bland, who shared the lead with Henley after the second round, plummeted down the leaderboard to one over with a brutal round of 77 punctuated by the 48-year-old putting his approach shot in the water on 18.
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