Paul Casey was one of the last of 53 players to make the cut on Friday at the 2018 Masters. So, that means the Valspar Championship winner goes out in the first tee time in Saturday's third round because he was the first in the house at 5-over 149.
Players who go out alone in the weekend rounds of the Masters have the option of playing with a non-competing marker -- that is, a person who plays alongside you but whose score doesn't count in any way. It's so the competing player has someone to keep their score and so they can maintain a pace to which they're accustomed and the lone player doesn't go at a speed that throws off the groups following him.
Typically at the Masters, when a player has a non-competing marker play alongside them, the man that gets the call is Jeff Knox.
Jeff Knox is an Augusta National Golf Club member who has the chops to keep up with many of the top pros, particularly on his home course. Knox owns the Augusta National course record of 61 from the member tees. His best score from the Masters tees is a very admirable 69.
Knox is on the Masters committee that sets the hole locations for each competitive round, and, since 2003, he's been the official marker of sorts (though the club can designate anyone to be the marker).
For Knox, this would be his ninth Masters appearance and 16th Masters round as a non-competing marker. Last year, Knox played two rounds, alongside Steve Stricker, then Thongchai Jaidee. Knox shot 77 both times. Stricker shot 73, while Jaidee shot 72. Knox played with Bubba Watson in the 2013 Masters. He's beaten Rory McIlroy straight-up.
Knox can play.