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Jordan Spieth opened the 2015 British Open as the betting favorite with 9/2 odds. It only took 18 holes for oddsmakers to install a new favorite. Dustin Johnson opened the tournament with a 7-under round 65, good enough for a one-stroke lead and to make him the new favorite. Johnson is now a 10/3 favorite to win with Spieth second at 4/1, according to Bovada.
Spieth's odds dropped, but only slightly as he opened with a 5-under round of 67. He's two shots off of Johnson's lead who opened the tournament as the second favorite at 12/1. The two battled down to the 72nd hole at the U.S. Open and if the odds prove true, are in for another head-to-head showdown for a major championship. Johnson played beautifully on Thursday combining his length off the tee with a hot putter to card the round of the day.
Jason Day is right in the thick of the leaderboard at 6-under and is one of the favorites. He's a 9/1 favorite, the third best odds. Louis Oosthuizen at 14/1 and Zach Johnson at 16/1 round out the top five. Rickie Fowler had the third-best odds entering the tournament at 16/1. He mustered only an even-par opening round and the result was a huge drop in his odds to 40/1.
Fowler's drop was significant, but no where near the biggest fall. That would belong to Tiger Woods. Woods was a 20/1 favorite heading into the first round. He then proceeded to card a 4-over round of 76 to fall 11 shots off the lead. He was completely removed off Bovada's betting board, which run odds up to 1000/1.
Here is a complete look at the betting odds from Bovada heading into the second round.
| Player | Odds |
| Dustin Johnson | 10/3 |
| Jordan Spieth | 4/1 |
| Jason Day | 9/1 |
| Louis Oosthuizen | 14/1 |
| Zach Johnson | 16/1 |
| Danny Willett | 22/1 |
| Adam Scott | 28/1 |
| Charl Schwartzel | 28/1 |
| Branden Grace | 33/1 |
| Luke Donald | 35/1 |
| Justin Rose | 40/1 |
| Phil Mickelson | 40/1 |
| Retief Goosen | 40/1 |
| Rickie Fowler | 40/1 |
| Robert Streb | 40/1 |
| Kevin Na | 50/1 |
| Paul Casey | 50/1 |
| Paul Lawrie | 50/1 |
| Sergio Garcia | 50/1 |
| Marc Warren | 55/1 |
| Tommy Fleetwood | 65/1 |
| Bubba Watson | 80/1 |
| Martin Kaymer | 80/1 |
| Matt Kuchar | 80/1 |
| Brooks Koepka | 100/1 |
| David Howell | 100/1 |
| Henrik Stenson | 100/1 |
| Matt Jones | 100/1 |
| David Lingmerth | 150/1 |
| Greg Owen | 150/1 |
| Hideki Matsuyama | 150/1 |
| Jimmy Walker | 150/1 |
| Kevin Kisner | 150/1 |
| Lee Westwood | 150/1 |
| Patrick Reed | 150/1 |
| Webb Simpson | 150/1 |
| Marc Leishman | 175/1 |
| Alexander Levy | 200/1 |
| Bernd Wiesberger | 200/1 |
| Ryan Palmer | 200/1 |
| Shane Lowry | 200/1 |
| Thomas Bjørn | 200/1 |
| Anirban Lahiri | 250/1 |
| Brandt Snedeker | 250/1 |
| Ernie Els | 250/1 |
| Francesco Molinari | 250/1 |
| Graeme McDowell | 250/1 |
| Graham De Laet | 250/1 |
| Jordan Niebrugge | 250/1 |
| Marcel Siem | 250/1 |
| Rafa Cabrera Bello | 250/1 |
| Ross Fisher | 250/1 |
| Steven Bowditch | 250/1 |
| Tyrrell Hatton | 250/1 |
| Brendon Todd | 300/1 |
| Geoff Ogilvy | 300/1 |
| Harris English | 300/1 |
| Jamie Donaldson | 300/1 |
| Jim Furyk | 300/1 |
| Russell Knox | 300/1 |
| Andy Sullivan | 400/1 |
| Anthony Wall | 400/1 |
| Billy Horschel | 400/1 |
| Eddie Pepperell | 400/1 |
| Gary Woodland | 400/1 |
| Hunter Mahan | 400/1 |
| Ian Poulter | 400/1 |
| J B Holmes | 400/1 |
| Padraig Harrington | 400/1 |
| Stewart Cink | 400/1 |
| Cameron Tringale | 500/1 |
| Charley Hoffman | 500/1 |
| Danny Lee | 500/1 |
| Jason Dufner | 500/1 |
| John Senden | 500/1 |
| Richie Ramsay | 500/1 |
| Rikard Karlberg | 500/1 |
| Romain Langasque | 500/1 |
| Thongchai Jaidee | 500/1 |
| Greg Chalmers | 600/1 |
| Oliver Schniederjans | 600/1 |
| Paul Dunne | 600/1 |
| Ashley Chesters | 1000/1 |