Leona Maguire opened her Olympic golf campaign with an even par round of 71, while team-mate Stephanie Meadow finished a shot back with a 72 on Wednesday.

Maguire sits just outside the top 20, tied for 23rd, while Meadow is tied 36th in the 60-player field.

However, tournament officials have warned that the competition could be reduced to 54 holes due to bad weather.

Heavy rain is forecast for the weekend, threatening the final round on Saturday.

Sunday would normally be used if Saturday is a wash out, but that may not be possible and players have been advised not to play two rounds in one day due to the high temperatures, which could reach 36C on Thursday.

Maguire never moved under par, responding to bogeys at holes four, 11 and 16 with birdies on five, 14 and 17. She recovered well on the last after finding sand with her second shot, but made four and saved par.

Her score left her five strokes off clubhouse leader, Sweden's Madelene Sagstrom, who shot an impressive 66.

The Cavan woman was the first of two Irish players taking part, with Meadow starting later.

The Jordanstown woman managed a par save from the sand on the par 3 fourth hole, but found more trouble on the par 4 sixth, after a poor approach shot, which bunkered short of the green and resulted in a bogey.

A bad start to the back nine saw Meadow drop to three over after successive bogeys on the 10th and 11th, however, she rallied later in the round with birdies on the par 3 16th and par 4 17th before parring the 18th to finish one over with a 72.

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Speaking to RTÉ Sport afterwards, Maguire said: "I felt like I hung in well."

"I didn't get off to the best of starts but made some good pars, got a couple of birdies in there. You can't win it on the first day but you can definitely lose it.

"My game has been in good shape over the last few weeks and it's just trying to do that week in, week out. Golf is a funny sport - you're not guaranteed anything no matter how good your last round is.

"I'm just trying to be patient. I did that last week at Evian. That 61 was patience all week and then it just broke for me on Sunday. I'm going in with the same mindset here this week."

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This is Maguire and Meadow's second Games, and Maguire said her experience from 2016 is standing to her.

"Rio, I was just happy to be there," she admitted.

"It was a bonus week for me as an amateur - I was just taking it all in. This year it's a bit more like a regular tour event. It's the same field pretty much every week on the LPGA Tour.

"It's more concentrated with the best players [here]. I'm definitely trying to content as high up that leaderboard as I can this week."

Meanwhile, Meadow said she was happy with the finish to her round.

"I had three over coming into the last three holes. I knew if I could just a couple coming in I could keep myself somewhere around the mark, and thankfully I made two putts," the 29-year-old said.

"I did not have my best stuff today. It's very hot and there's a lot going on and I'm just trying to keep going and hopefully shoot better tomorrow."

Caddies suffer in high temperatures

Players have also been advised not to play more than 18 holes in a day due to the extreme heat, which has seen two caddies unable to complete rounds at Kasumigaseki Country Club.

On Tuesday, US Women's Open champion Yuka Saso had to replace her caddie due to the heat and American Lexi Thompson lost her regular caddie, Jack Fughum, on the 15th hole of the first round.

"I was so worried about him, it's so hot out there," Thompson said. "I'm from Florida and I'm still not used to that bad of heat.

"I just hope that he's okay and he gets the hydration he needs, the nutrients tonight to go into the next few days. If not, I'll figure something else out. I just want him to be healthy."

US coach Donna Wilkins stepped in to carry Lexi Thompson's bag for the final holes

A notice to players from the IGF's competitions committee read: "Please be advised that based on our medical advisor's input, playing more than 18 holes in one day is not advisable.

"Also, due to a poor weather forecast beginning on Saturday through Sunday, the women's Olympic golf competition may be reduced to a 54-hole competition. Further information will be published following the conclusion of round two.

"In addition, for tomorrow's play we will implement additional heat mitigation measures including: Umbrellas available on the first tee to all players/caddies, roving carts with ice and cooling towels and volunteers with umbrellas on each tee."