Dustin Johnson (USA), 33
• World ranking: 1 • Major titles: 1
The long hitter won his first Major at the US Open last year but has performed poorly in recent Majors, missing the cut at last year's PGA Championship and at last month's US Open, either side of sitting out the Masters with a back injury.
His recent form on Tour has also been disappointing as he regains his fitness, but he remains the favourite with most bookmakers.
Jordan Spieth (USA), 23
• World ranking: 3 • Major titles: 2
The Texan, who turns 24 next Thursday, is already remarkably successful. Victory at the Travelers Championship last month allowed him to match Tiger Woods in reaching 10 Tour wins at such a young age.
However, his two Major titles came back-to-back in 2015. He has struggled to match that feat since finishing second at last year's Masters after blowing a five-shot lead on the final day. He was tied for 35th in the US Open last month.
Rory McIlroy (Nir), 28
• World ranking: 4 • Major titles: 4
The last Open at Birkdale was won by a golfer from across the Irish Sea in Padraig Harrington, so McIlroy will be hoping that is an omen.
The only time he got his hands on the Claret Jug came three years ago just the other side of Liverpool at Hoylake, but his form is not the best. He is winless this year. He was joint-seventh at Augusta in April and missed the cut at the US Open. He also missed the cuts at the recent Irish Open and Scottish Open.
Jon Rahm (Esp), 22
• World ranking: 7 • Major titles: 0
The eye-catching Spaniard's rise has been staggering. He made the cut at last year's Open in just his third event as a professional, before claiming his first PGA Tour title at Torrey Pines earlier this year.
He followed that up with a run to the WGC World Matchplay final and his runaway victory at the Irish Open. Tipped by many to win multiple Majors, there is no reason why he cannot get that ball rolling in north-west England.