Tsitsipas has been up and down for a very long time, with the last few matches being somewhat disappointing. Indoors has always been a good season for him, as his biggest trophy came at the ATP Finals years ago, which was an indoor event.
He can play well in these conditions thanks to his serve, which is a major weapon and was a major weapon for much of today's match. The win over Auger-Aliassime is significant as the Canadian is a really strong indoor player, as well as being in good form after the trophy run in Basel last week.
Auger-Aliassime opened well, getting to the early break point, but wasted both of them. Tsitsipas then broke his opponent a few games later to take the lead, and he never let it go despite facing a break point in the final game of the set.
His serve was working well, and the forehand didn't disappoint either. Tsitsipas outplayed Auger-Aliassime comfortably, outhitting him from the baseline 18>7 in winners.
The second set opened better for the Canadian as he had a 3-0 lead after the first game. It's not completely out of character for Tsitsipas to complicate matches, so this wasn't a huge surprise.
Auger-Aliassime held the lead for the rest of the set and nearly finished off the set on the serve of Tsitsipas. He wasted three set points there, and then one more on his own serve before Tsitsipas broke for the 5-4 score. He would force a tiebreak and then outplay the Canadian 7-4 to win the match in two sets.
Auger-Aliassime actually outhit Tsitsipas in the end, but the Greek player simply played better in the crucial moments, which was enough to win.