July 22 (Reuters) - Play was suspended for the day at the Barbasol Championship on Sunday due to inclement weather before the four co-leaders could tee off at Keene Trace Golf Club in Nicholasville, Kentucky.

The final round will resume on Monday at 7:30 a.m. ET (1130 GMT) with American co-leaders Hunter Mahan, Robert Streb, Troy Merritt and Tom Lovelady at 18-under-par for the week and among the eight golfers who had yet to start the final round.

Competition had been interrupted twice already in the round, the first time for nearly four hours because of heavy rain. When play finally resumed, it lasted for only 12 minutes as lightning forced another suspension that lasted 79 minutes.

Twenty-one golfers managed to complete their rounds before play was abandoned, including Americans Kyle Thompson (68), Matt Atkins (69) and Rob Oppenheim (69), who were in the clubhouse at 11-under for the week. (Reporting by Frank Pingue in Toronto; Editing by Ian Ransom)