McEwen (5-0) scored four points in the fourth end and broke a 6-6 tie with a single in the eighth. It was his second victory of the day after he beat Toronto's John Epping (3-2) 7-4 in the morning draw.
Jacobs (3-2), won his final game of the evening, 7-4 over Winnipeg's Jeff Stoughton (2-3). Jacobs scored two points each in the first and fourth ends, and added three more in the sixth to seal the victory after seven ends.
Stoughton topped Switzerland's Sven Michel 6-2 earlier in the day, and Epping downed Niklas Edin of Sweden 7-4 in the evening draw.
Kevin Martin (3-2), who announced Friday that he'll retire following the tournament, scored singles in the fifth, sixth, and seventh ends to beat Calgary's Kevin Koe 5-2 in the afternoon draw. Earlier in the day, Martin defeated Scotland's David Murdoch 5-3.
Koe (4-1) edged Glen Howard (1-4) of Coldwater, Ont., 8-6 in the afternoon draw. Brad Gushue is 4-1 after toppling Saskatoon's Steve Laycock 8-4 in Draw 11.
and all clinched playoff spots.
On the women's side, Switzerland's Silvana Trinzoni, Sweden's Margaretha Sigfridsson, and Scotland's Eve Muirhead are tied for top spot with 4-1 records.
Ottawa's Rachel Homan, Saskatoon's Stefanie Lawton, and Winnipeg's Jennifer Jones are all 3-2 with clinched playoff berths.
Homan scored three points in the eighth end to edge Michele Jaggi of Switzerland 7-5 in her only match of the day Friday morning. Jones, meanwhile, fell 7-1 to Sherry Middaugh of Coldwater, Ont., in her morning matchup.
Lawton staved off a late comeback attempt by Calgary's Crystal Webster for a 5-3 victory in the afternoon draw.