Toyko Olympics: Sepp Straka holds early lead in Men's Golf Competition as Paul Casey starts strongly

Paul Casey made an encouraging start to his Olympic bid to get within four strokes of the early lead during a weather-affected opening round of the Men's Golf Competition.

The Englishman carded a bogey-free 67 at the Kasumigaseki Country Club, where play was suspended for over two hours due to the threat of lightning, to stay in touch with early pacesetter Sepp Straka.

Casey took advantage of the par-five fifth and followed a 25-foot birdie at the seventh by picking up a shot at the next, seeing him reach the turn in 33, before holing from close range to add another at the par-five 14th.

"It is a solid start," Casey said. "I don't know what the winning score is going to be - we've predicted 15, 16 (under par), something like that. We will have to see how it pans out. You've got to just eliminate mistakes, and what I didn't want to do was shoot myself in the foot."

Straka birdied four of his final six holes to post a round-of-the-day 63 and claim a one-shot advantage over Thailand's Jazz Janewattananond, who posted four consecutive birdies around the turn on his way to a seven-under 64.

"I felt comfortable with my game going into this week," Straka said. "I hadn't played great over on the PGA Tour the last few weeks, but my putting was really the reason and I just switched up my routine on my putting and it's worked out."

Thomas Pieters, who finished fourth at the 2016 Rio Games, followed a hole-out eagle at the 11th by birdieing his final two holes and jumping into tied-third with Carlos Ortiz, while Juvic Pagunsan - who skipped The Open to prepare for the Olympics - one of three players sitting on five under.

Patrick Reed, a last-minute invite after Bryson DeChambeau's coronavirus-enforced withdrawal, is in the group on three under that contains compatriot Xander Schauffele, Si Woo Kim - in need of a medal this week to avoid military service in South Korea - and Norway's Viktor Hovland.

Masters champion Hideki Matsuyama was unable to build on his fast start, birdieing four of his opening eight holes before slipping back to a two-under 69, with Rory McIlroy also six strokes back after mixing four birdies with two bogeys during his round.

Champion Golfer Collin Morikawa is also sitting tied-20th, with Tommy Fleetwood's final-hole double-bogey seeing him card a one-under 70 and putting him on the same score as Shane Lowry.

Forty of the 60-man field are under par after a low-scoring opening day, while world No 4 Justin Thomas is eight off the pace after making par on all 18 holes to post a level-par 71.