Mackey reached Yentna at 8 p.m., nine hours after he was the first to leave the Knik Lake start line at 11 a.m.
Mushers started in two-minute increments amid heavy snow and Santos didn't hit the trail until 11:58 a.m. He reached Yentna at 8:55 p.m., but with the time differential factored in, he leads Mackey by three minutes.
Jake Berkowitz of Big Lake, who was second to reach Yentna, arriving at 8:17 p.m., trails Santos by four minutes. Ray Redington Jr. of Knik is eight minutes back in fourth place.
The race will end at Knik Lake sometime this afternoon. An awards banquet is set for 7 p.m. at the Knik Bar.
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