UFC officials announced the fight on Tuesday.
Technically, Josh Thomson moves to the UFC from Strikeforce, but at one time he was considered the uncrowned champion of the lightweight division that competed inside the Octagon.
Unfortunately at the time, the UFC opted to do away with the 155-pound weight class, so Thomson moved on and ended up winning the Strikeforce title. He also managed to engage in an epic trilogy of fights with current Strikeforce titleholder Gilbert Melendez.
Now Thomson faces a tough test for his return to the UFC as he faces off with former Ultimate Fighter winner Nate Diaz.
Diaz books his next fight just over a month after his loss to UFC lightweight champion Benson Henderson at UFC on Fox 5 in December. Now Diaz will try to get back on track and face a fellow local area fighter in Thomson, who trains out of the American Kickboxing Academy in San Jose, Calif.
Diaz vs. Thomson is the latest addition to the UFC on Fox 7 card taking place at the HP Pavilion in San Jose on April 20, which features several UFC vs. Strikeforce fights including the main event pitting Benson Henderson against Gilbert Melendez.