Pouille is a former world number 10 who was an amazing player at the height of his career. In 2016 he defeated Rafael Nadal in the US Open en route to the quarter-finals. He reached the quarter-finals at both the US Open and Wimbledon. His peak at Roland Garros was in the 3rd round and the Australian Open in 2019 gave him his best grand slam result (semi-final).
His career fell off since then as he battled depression and alcoholism but he's back to his former self trying to resurrect his career. It hasn't been going that well as he's ranked outside of the top 500 in the rankings but he made a surprise run here to qualify and it meant the world to him.