The 29-year-old defeated Cobolli 6-1, 4-6, 6-4, 6-7 (5), 6-1 in five sets to secure his long-awaited Grand Slam victory.
Mirra Andreeva has become the youngest woman to win the Roland Garros since Monica Seles in 1992.
From the beginning of his career, Nadal was a trendsetter.
Berlin trial against Alexander Zverev on assault charges ended without a verdict on Friday, just ahead of his French Open semi-final match.
“Congratulations girls for playing a great match,” Mertens said.
The highly-anticipated contest between the world number one and the two-time Roland Garros champion ended after two high-octane sets.
The four-time major champion said in a statement that she picked up the injury last week in Madrid.
They beat second seeds and Roland Garros champions Pierre-Hugues Herbert and Nicolas Mahut.
Djokovic defeated Matteo Berrettini in 6-7(7-4), 6-4, 6-4, 6-3 at Wimbledon to achieve the feat.
Djokovic now needs one more major title victory to tie Rafael Nadal and Roger Federer who jointly have 20 title wins.
