Rank outsider Louis Oosthuizen stood on the cusp of British Open glory on Sunday, taking a four-stroke lead into the final round.

The 27-year-old South African carded superb rounds of 65, 67 and 69 to set up a 15-under par winning position and only England’s Paul Casey with rounds of 69, 69 and 67 managed to hang onto his coattails.

The rest of the field was led by Martin Kaymer, and even the German said he did not expect to close the gap on the leader from seven strokes back conceding that it might well be a two-horse race.