DeChambeau swept to his maiden victory on the European Tour at Emirates Golf Club 12 months ago, finishing on 24 under par and seven shots clear of nearest challenger Matt Wallace.
The Californian will tee off at 0800 and will play alongside Westwood, who triumphed at the Abu Dhabi HSBC Championship presented by EGA last week, in the first two rounds.
Joining them is 11 time winner on the European Tour Henrik Stenson as he begins his 2020 season in Dubai.
France's Victor Perez and England's Matthew Fitzpatrick are paired together in the group starting at 1230 after finishing joint second in Abu Dhabi and they are joined by seven time winner on The European Tour Bernd Wiesberger.
Amateur Joshua Hill, the 15-year-old who made more headlines last week ahead of his European Tour debut by beating World Number One Brooks Koepka in a nine-hole friendly, is in the second group on the course with Belgium's Thomas Detry and Japan's Masahiro Kawamura.
Fellow amateur Jayden Trey Schaper starts at 1310, fresh from his impressive tied for sixth finish at the South African Open hosted by the City of Johannesburg.