Rahm cruised to a six-shot win at Portstewart Golf Club, an effort that helped his odds plummet from 25/1 to 12/1 over the course of a week at the Westgate Las Vegas Superbook. He is now even with Jordan Spieth, who won the Travelers Championship last month, and behind only Dustin Johnson who remains a 10/1 favorite.
Rahm tied for 59th in his Open debut last year at Royal Troon, and finished T-27 at the Masters this year before missing the cut at Erin Hills.
Here's a look at the betting odds for several contenders, with the first round at Royal Birkdale now only 10 days away:
10/1: Dustin Johnson
12/1: Jon Rahm, Jordan Spieth
25/1: Henrik Stenson
50/1: Patrick Reed