The Offaly man dropped a pair of shots on his last two holes.
Rickie Fowler and Xander Schauffele made US Open history last night.
Their opening rounds of 62 were the lowest in the tournament's history, and equalled the record of the lowest ever round at any Major.
They'll go into day 2 in Los Angeles on 8-under par.
Rory McIlroy also started well.
He is tied fifth on 5 under par after a 65.
Shane Lowry and Seamus Power are 2 over par, with Padraig Harrington and amateur Matt McClean on 3 over.
Lowry reflected on a mixed round by saying: "Some good golf in there…Disappointing finish, but roll on tomorrow"
Some good golf in there…Disappointing finish but roll on tomorrow @usopengolf 💪🏻☘️
— Shane Lowry (@ShaneLowryGolf) June 15, 2023
pic.twitter.com/iCiLLdjLGV
Our coverage of the US Open is with thanks to Keenan Bauer Motors, Mullingar.
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