(Reuters) - Defending champion Jordan Spieth and fellow Americans Zach Johnson and Bryson DeChambeau will form an eye-catching grouping for the first two rounds of next week's U.S. Open in Oakmont, Pennsylvania.

World number two Spieth, who won last year's title by one shot after a thrilling finish at Chambers Bay, reigning British Open champion Johnson and DeChambeau will start Thursday's opening round on the 10th tee at 8:35 a.m. ET.

The all-American trio will then set off from the first tee at 2:20 p.m. in Friday's second round at Oakmont Country Club.

In keeping with tradition, tournament officials placed the defending champion in the same group as the British Open champion and last year's U.S. Amateur winner (DeChambeau).

Spieth, seeking his third major title after clinching his first at the 2015 Masters, will aim to rebound from his stunning back-nine collapse at this year's Masters when he threw away the title after leading by five strokes with nine holes to play.

Jason Day, the Australian world number one and winner of last year's PGA Championship, will tee off from the first hole at 2:20 p.m. on Thursday, along with compatriot Adam Scott and South African Louis Oosthuizen.

Northern Irish world number three Rory McIlroy, the 2011 U.S. Open champion at Congressional, has been paired with Masters winner Danny Willett of England and fifth-ranked American Rickie Fowler.

In other notable groupings, former world number ones Lee Westwood and Luke Donald of England and Germany's Martin Kaymer have been put together while Japan's Hideki Matsuyama will play with Spaniard Sergio Garcia and long-hitting American Dustin Johnson.

Fan favorite Phil Mickelson, a runner-up in his national championship a record six times without ever winning the title, will start out with 2013 U.S. Open champion Justin Rose of England and Sweden's Henrik Stenson.

In another themed group, three former U.S. Open champions have been put together with South African Ernie Els (1994 and 1997) set to play alongside American Jim Furyk (2003) and Argentina's Angel Cabrera (2007).

Cabrera won the U.S. Open when it last was held at Oakmont, which will host the June 16-19 championship a record ninth time.

(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Andrew Both)