But the fightback was shortlived and the world number two, who was watched by Brazilian footballer Neymar, Miami Heat basketballer Jimmy Butler and 2009 US Open champion Juan Martin del Potro, sealed victory on his first match point.
“He’s a great athlete. He reaches almost every ball,” Alcaraz said of Monfils.
“But at the same time, with my forehand, my best shot, I tried to move him around the court, tried to get him tired a little bit.
“It’s kind of difficult to stay focused on the match, having such legends from every sport.
“It’s a great opportunity to have them here, to talk with them a little bit. It’s great to put on a show in front of them.”
Zverev limited his unforced errors, converted his two break-point opportunities and saved four of the five break points he faced against Eubanks.
“It was a difficult match. I thought he was in control of it throughout the first set,” he said. “I was just hanging on and sometimes that is just what you need to do.”
Eubanks had a chance to serve out the first set at 5-3 but was denied by Zverev, who broke the American again early in the second set to build a 3-0 lead. Zverev later had to save three break points to serve out the match.
His next opponent will be Russian 15th seed Karen Khachanov, who converted his fifth match point to secure a 6-1 5-7 7-6 (7-5) win over Argentine 20th seed Francisco Cerundolo.
