McEwen, from Winnipeg, sits atop the men's standings at 4-0 at the season's final Grand Slam of Curling stop.
John Epping, from Toronto, downed Saskatoon's Steve Laycock 7-1 in afternoon action and is 3-0 after nine draws to sit second.
In other evening play, former Olympic champion Brad Gushue of St. John's, Nfld., beat Edmonton's Brendan Bottcher 5-4 to improve to 3-1 — good for a third-place tie with Calgary's Kevin Koe, who beat Switzerland's Sven Michel 7-3. Bottcher is sixth at 2-2.
Also, Winnipeg's Reid Carruthers dowed Brad Jacobs of Sault Ste. Marie, Ont., 5-4. Jacobs is alone in fifth spot at 2-1 while Carruthers is in a four-way tie for seventh at 1-2 with Laycock, Glenn Howard of Penetanguishene, Ont., and Winnipeg's Jeff Stoughton, who edged Howard 5-4.
Edin and Michel are in last place with 0-4 records.
On the women's side, Switzerland's Alina Paetz sits alone in first place through eight draws with a 3-0 record after toppling Russia's Anna Sidorova 6-5.
Ottawa's Rachel Homan fell to Edmonton's Val Sweeting 9-2, Sherry Middaugh of Coldwater, Ont. defeated Switzerland's Silvana Tirinzoni 7-6, Winnipeg's Jennifer Jones beat Binia Feltscher of Switzerland 6-5 and Winnipeg's Kristy McDonald slipped past Sweden's Margaretha Sigfridsson 5-4.
Homan, Sweeting and Middaugh are tied for second at 3-1 while Scotland's Eve Muirhead is fifth at 2-1. McDonald's 2-2 record is good for sixth spot as Switzerland's Binia Feltscher, Edmonton's Heather Nedohin, Sidorova and Jones are tied for seventh at 1-2.
Tirinzoni is 1-3 while Sigfridsson remains winless at 0-4.
There are 12 teams entered in both the women's and men's draws. Round-robin play is scheduled to continue Friday.
The playoffs will begin Saturday and the finals are scheduled for Sunday.