Andrew Coltart carded a 3-under 69 to finish alongside Jose Manuel Carriles in a tie for fourth at 11-under-par 205.
Fraser held a slim lead over three players to start the day at Le Meridien Moscow Golf & Country Club and had a solid start with three birdies over his first seven holes.
The Australian added a birdie at the 12th to reach 15 under and opened a three-shot advantage over the field with back-to-back birdies starting at the par-four 14th.
The 25-year-old struggled down the stretch, however, with bogeys on two of his last three holes for a round of 4-under 68, which dropped him back into a share of first.
'I was very disappointed with my finish today,' said Fraser. 'I bogeyed 16 after a bad tee shot then hit the ball in the water on 17 and made a good par in the end. Then I hit a bad tee shot on the last and had to settle for bogey.
'Apart from that, it was probably the best I've played all week for 15 holes. I didn't really putt all that well and it's a good thing to be 6 under for the round at that stage and not be putting that well. I will take some positives from that.'
Wiegele stood at 13 under par through 12 holes but the 25-year-old from Austria caught fire coming home. He ran off back-to-back birdies from the 17th to close out his round and join the Fraser atop the leaderboard.
'I was a little nervous at the start today, being in the last game of my first European Tour event but then I got a bit more solid with my swing and I played really well after that,' said Wiegele. 'I had a good finish again, the same as I had yesterday. I hadn't really thought about being in the lead or tied for the lead because Marcus was playing so well and I was three behind at one point. I just wanted to get into a good position and a birdie-birdie finish is always great.'
Ryles also had a good start to his round with four birdies over his first 10 holes but the Englishman soon found trouble with a pair of bogeys starting at the 12th.
The 23-year-old responded well with an eagle at the par-5 15th. He added a birdie at the 17th but a bogey at the last left him one shot back.
'That was a big, big eagle,' said Ryles. 'I was deciding about whether or not to go for the green in two but I decided to go for it and hit a great 3-wood 248 yards onto the green and then sank a 40 foot putt for eagle.'
Garry Houston fired a 6-under 66 to join Steve Bowditch, Peter Hanson, Nicolas Vanhootegem, Jesus Maria Arruti and Kalle Brink.
This event features players from the European Tour and the Challenge Tour. This is the tournament's first year on the European Tour.