SAULT STE MARIE, Ont. — Brad Gushue keeps rolling through the third Grand Slam of Curling tournament of the season.

Gushue, of St. John's, N.L., edged Greg Balsdon of Kingston, Ont., 7-6 on Thursday to improve to 3-0 in round-robin play at the National.

Gushue went undefeated in winning the two first Grand Slam events — the Tour Challenge in September and the Masters last month.

Gushue, who leads Pool A, scored a deuce in the seventh end Thursday night to go up 7-5 over Balsdon (1-2). Balsdon earned a single in the eighth.

Winnipeg's Jason Gunnlaugson (3-0) leads Pool B while South Korea's Chang-Min Kim tops Pool C, also at 3-0.

Gunnlaugson defeated Calgary's Kevin Koe 8-6 in the afternoon draw to move into sole possession of first place in their pool. Koe fell to 2-1.

In other night draw matchups, Winnipeg's Mike McEwen beat Scotland's Bruce Mouat 7-2, Koe edged Brad Jacobs of Sault Ste. Marie, Ont., 6-4 and Winnipeg's Pat Simmons topped China's Rui Liu 7-5.

In women's play, Tracy Fleury of Sudbury, Ont., improved to 4-0 in Pool A with a 7-4 win over Winnipeg's Michelle Englot. Fleury started the day by beating Jacqueline Harrison of Mississauga, Ont., 7-5.

Val Sweeting of Edmonton is in first place in Pool C at 4-0. She downed Calgary's Chelsea Carey 8-0 and China's Bingyu Wang 8-4.

Casey Scheidegger of Lethbridge, Alta., and Winnipeg's Jennifer Jones top Pool B at 3-0.

Round-robin play continues through Friday ahead of the weekend playoffs.