Rooney made his England return and helped raise money for his foundation as Gareth Southgate's men beat the USA 3-0 at Wembley.
The former Manchester United skipper was a second-half substitute and took the armband but could not add to his record tally of 53 goals.
Guzan admitted he knew England's players were trying to set up Rooney for a fitting finale but he wasn't going to let him score.
"I was saying to our defenders that obviously they were trying to get him to score, so we had to get close to him," Guzan said.
"You laugh and joke about it afterwards but in the midst of the game you're not really thinking about it. You're just trying to keep the ball out.
"We shared some words in the tunnel afterwards. It's been a good move for him going to America."