The second round was completed Saturday morning after darkness forced the suspension of the second round Friday night. The third round was completed without any weather delays.
Butcher opened on the back nine at Wild Bluff Country Club and collected two birdies in his opening four holes. He added back-to-back birdies at 16 and 17 to take a substantial lead into the back nine.
He only managed one birdie on the second nine, at the par-4 third hole, but still holds a four-shot lead with one round to play.
Butcher played steady throughout the first two rounds but was did in by mistakes. He four-putted for a double bogey on Thursday and triple bogeyed the 15th in the second round.
'Like the first two days, I did everything right but this time I eliminated the bad hole,' said Butcher. 'Today's round is all just a blur. All I remember is joking around. There is a lot of standing around out there at times, and the stress relief is always good.'
With this being the final tournament on the Canadian Tour 2003 docket, players are jockeying for position on the Order of Merit table. The top-two money winners after this week earn exemptions into the second stage of PGA Tour Q-School.
Butcher does not have a chance at that but is still focused on retaining his playing privileges for next season.
'I know there is a big race going on, and I don't want to spoil anybody's day, but I need to win to keep my card here,' said Butcher. 'I'm just trying to control what it is I do. Let the chips fall where they may and see what happens.'
McGuigan shot a 1-under 71 on Saturday to finish at 4-under-par 212.
Jon Mills and Mario Tiziani posted matching rounds of 4-under 68 in the third round to join Chris Wall, who shot even-par 72, in a tie for third place at 3-under-par 213.
Brad Sutterfield (70), Bryan Wright (71), David Burbidge (72), Michael Harris (72) and Michael Sabo (72) are tied for sixth place at minus-2.