Minjee Lee and Hannah Green five shots off the leader after even par rounds on a stifling opening day of the Olympic women’s golf competition.

It was 35 degrees and humid at Kasumigaseki Country Club and players were desperately seeking water and shade, while American Lexi Thompson’s caddy had to be taken to hospital with heat stroke.

“It was bloody hot!” Minjee Lee said of the tough conditions.

Lee had a colourful scorecard as she combined five birdies with five bogeys in her round of 71.

In her pre-tournament press conference, the Evian Championship winner discussed the importance of a good start to be in medal contention, but the conditions have caused her to adjust her thinking.

“I’m just going to take it day by day because it’s so hot,” Lee said.

“I have high expectations of myself - that’s why I’m so disappointed in the even par - but if you look at it overall it’s probably not too bad of a start.”

A bogey on the par-4 3rd was an early hiccup, but she responded immediately by nearly making a hole-in-one on the 4th and the resulting birdie started a stretch of three birdies in five holes to be among the leaders.

She showed her class with approach shots that stopped within two metres of the hole to make birdies at the 6th and 8th, but she could not maintain the momentum.

Back-to-back bogeys at nine and ten followed by back-to-back birdies at eleven and twelve had Lee constantly shuffling up and down the leaderboard.

However, bogeys at the 14th and 17th settled her in the pack of 13 players at even par.

“I made really soft bogeys, so tomorrow I’ll just try and eliminate them and make as many birdies as I did today.”

Lee, in her second Olympic Games, admitted to being “a little bit emotional” at the first tee this morning.

“It does (mean a lot to be an Olympian), more than I thought it would,” she said.

Fresh off a wet Perth winter, Hannah Green admitted that she had to make a bigger adjustment than her rivals who have been playing golf in the northern hemisphere summer.

“It was hard to concentrate out there in the heat,” Green said.

“I’m not the greatest in humidity, so I think I did a good job with my hydration and I need to find the shade as much as possible - just not with my tee shot.”

Despite the challenging conditions, Green was simply thrilled to be back on the golf course and making her Olympic debut was a nice bonus.

“I was just super excited because I haven’t played golf in so long and there've been so many wins for the Aussies - obviously in the Olympics but as well in golf all around the world - I was excited to get back out here,” she said.

“Now that I can say I’m an Olympian is pretty cool.”

Green fought back from a three putt double bogey at the third to gradually work her way up the leaderboard with birdies at five, eleven and sixteen.

Her tee shot to around five and a half metres on the par-3 16th and the resulting birdie putt was the highlight of her round.

“I felt like I played a lot worse than the score,” she said.

“I missed a lot of greens and a lot of fairways, so that’s something I need to work on at the range.

“I definitely felt the rust - I don’t think I’ve ever been one to have a great first round back.”

Nevertheless, the West Australian believes she can improve coming into the weekend.

“Seeing Rory Sabbatini and CT Pan have great rounds on the last day, they weren’t really in it the whole week, so you never know what can happen,” she said.

The round of the day belonged to Sweden’s Madelene Sagstrom who went bogey free in her five-under round of 66.

Meanwhile, American world number one Nelly Korda shared second place with Indian Aditi Ashok at four-under par.

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