American star Lilian Vu holds a slender one-shot lead over world No.1 Lydia Ko going into the final round of the $5 million Aramco Saudi Ladies International thanks to a thrilling eagle on the final hole on the Royal Greens Golf & Country Club.

Vu, a three-time winner last season on the Symetra Tour, the official developmental golf tour of the LPGA Tour, put herself in touch of glory on her first outing this season after the eagle on the par-five 18 gave her a seven-under round of 65, one better than Ko’s six-under 66.

She now sits on 18-under with Ko one back and overnight leader Aditi Ashok on 16-under after a three-under 69, alongside former champion Emily Kristine Pedersen, who carded a seven-under 65.

Vu is eager to take the pressure off by adopting a fun approach on the course. She said: “I find I play my best when I’m having fun, so I’m just going to try and do that tomorrow. I was actually a little nervous coming here because it’s the start of my season, first tournament of the year for me. I felt kind of rusty coming through. Then once I started to trust myself the game just got better on its own.”

Vu felt she was at an advantage playing alongside world No. 1 Ko in the penultimate round, saying: “I have a lot of fun playing with her. I mean, when you play with good players you tend to play better, and she just hits the ball so well. It’s been fun.”

Of her eagle putt on 18 to leapfrog Ko and take the outright lead, she added: “I had a really long putt from the front the green, back left pin. It was about 24 paces, and I just hit and hope on that one.”

Lydia Ko. LET

A par on the last gave Ko a six-under 66, and a one-shot deficit going into the final round. She admitted she is looking to emulate Vu on Sunday and hopes that an aggressive approach alongside the American and Pederson in the final group will help her to career win no 26, an astonishing return for a 25-year-old.

She said: “We played for the first time on tour at the Scottish Open last year. I just really liked how she went about her business, really fast and really aggressive when it comes to play. So that’s something that I’m trying to work on — to be a little bit more aggressive and just commit to my shots and just let it rip. That kind of seems like the way she plays. It was fun to play alongside her and Aditi.

“It’s going to be a great showdown, especially if the wind is not as breezy as yesterday afternoon. I don’t know how many shots back is actually back, because you could possibly make a stretch of birdies and put yourself up there.”

Ashok couldn’t follow up her sensational first two rounds of 65 and 66 but was philosophical after three birdies in the final four holes kept her in touch, two off leader Vu. She said: “I think I hit it good today, created a lot of birdie chances. I just didn’t hole as many putts as the first two days, but I’m still happy with my game. Hopefully I can hit it as good but hole more putts.”

The Indian admitted words of encouragement from her dad, who is caddying for her in Saudi, helped her to stay positive. She said: “It was good actually. I was not holing many birdie putts, so halfway around he was like, stay patient; you’re hitting the ball really good. Just hearing that from your caddie, because I’m getting disappointed through the round, it was just nice to get a bit of pick-me-up and then finish with a couple birdies.”

Lexi Thompson put herself in with a shout thanks to an astonishing nine-under 63 which equalled the course record and left her five off the lead.

The American, who hasn’t dropped a shot in the second or third rounds of the tournament, said: “It was just overall a solid day out there. I chipped in on one. I guess kind of set the mood. I was just overall steady day. I just tried to stay in the moment, focus on what I did yesterday, because yesterday was a pretty solid round, too. I just tried to build off that and take it into today.”

Thompson, a major winner at the Chevron Championship in 2014, was another to benefit from some family encouragement — her brother is on the bag at King Abdullah Economic City. She said: “We just talk about the most random things or get deep into a conversation that just goes nowhere. But it’s amazing. He knows me so well and knows my game probably better than I do because we play together every day back home. I’m very lucky and blessed to have him out here.”