King had the fastest team into Cripple, but Mackey has won the last three races thanks in part to his ability to rest less than the competition.
Earlier in the day Dallas Seavey, the son of 2004 Iditarod champion Mitch, led the way into Cripple despite John Baker's sizeable head start out of Ophir.
Seavey won $3,000 in gold nuggets for being the first into the abandoned mining town, arriving at 1:26 a.m., an impressive feat for the 23-year-old -- his birthday was last week -- who holds the record for the youngest person to ever compete in The Last Great Race when he finished 51st in 2005. Seavey rose to 41st in 2007 and was a very strong sixth last year.
Baker, who apparently stopped on the trail for an extended period of time to rest or deal with a problem, checked in at 1:37 a.m. Martin Buser arrived at 5:03 a.m.
Bruce Linton joined the trio at 7:39 a.m. followed by rookie Michelle Phillips, who is continuing her strong showing, at 9:49 a.m. Robert Nelson arrived at 10:13 a.m.
Also Thursday, Karen Ramstead scratched in McGrath for personal reasons. The 45-year-old musher from Perryville, Alberta had 14 dogs still on her team when she made the decision at 8 p.m. She has run the Iditarod eight times before.
Contact Andrew Hinkelman at firstname.lastname@example.org and follow @KTUUSports on Twitter.