The Miami match that looked like a smooth ride after wins over Dzumhur and Moutet turned choppier when young American Brandon Michelsen started playing with fearless energy. Jannik Sinner, world No. 2, was not at his best and needed more than his racquet to get back on track. The team around him made the difference.

Why the box mattered

Stefan Cahill kept getting up from his seat to clap and push for energy. Simone Vagnozzi, who had arrived in Miami a few days later after a short break, stayed vocal with tactical tips. Two brief lines from Vagnozzi were picked up by the court microphones and they arrived at important moments of the match.

The first instruction, at 4-4 in the first set

When the score was 4-4, no break points had fallen yet. Michelsen had started strong on serve, but later began to give Sinner some chances. At the start of the ninth game Vagnozzi told Sinner, "Move with your legs, don't stand too far back on the second. Two steps, not three." That advice helped Sinner force three break points and take the score to 0-40. He was not able to convert those initial chances, not even a fourth at advantage, but the pressure paid off in the next game when he finally broke Michelsen to go 6-5.

The second instruction, at 2-2 in the second set

In the second set, at 2-2 and on Michelsen's serve, Sinner was under real pressure. Vagnozzi called for more aggression: "You push, it is fine if you make mistakes, but try it yourself." Sinner looked unsure and hit a couple of backhands into the net. Then he started to take the initiative and play more aggressively. He still lost the game and it became his toughest stretch, including suffering the first break of the tournament against him.

How it finished

A bit of luck arrived when the sun moved onto Michelsen's side of the court during his service games, though Sinner could not immediately take advantage. Later, a recovered serve and steady team support helped Sinner win a counterbreak. He kept his cool in the deciding tie-break and closed out the match. After a particularly nice point he tapped his finger to his ear to get the crowd's response, something he rarely does but clearly wanted that night.

What comes next

  • Sinner moves into the quarterfinals in Miami.
  • His next opponent will be American Frances Tiafoe, which raises the level of difficulty.

The match underlined how much a coach and a full team can influence tight moments. Two short sentences at the right time made a clear difference.