A target that Jordan Spieth thought, at the start of the year, was well out of his range suddenly seems as accessible as a drivable par 4. Spieth won his second consecutive start and his fourth title of 2015 on Sunday at the John Deere Classic to inch closer to golf’s summit.

If Spieth extends his winning streak next weekend at the British Open at St. Andrews, he will supplant Rory McIlroy as the world No. 1 while becoming the first player since Ben Hogan in 1953 to win the first three legs of the Grand Slam in a calendar year.

At the John Deere Classic, Spieth’s first competitive start since his victory at the United States Open and his only tuneup before heading to the Old Course, he closed with a three-under-par 68 to tie Tom Gillis at 20 under. Spieth, 21, defeated Gillis, a 46-year-old who has not won on the PGA Tour, with a par on the second hole of sudden death.

With McIlroy, 26, sidelined indefinitely with a badly sprained left ankle, the second-ranked Spieth’s coronation feels like a mere formality. Nobody on any tour has played better this season than Spieth, who has 11 top-10 finishes in 17 starts, not counting victories last December against quality fields at the Australian Open and the Hero World Challenge.