After a sluggish first half, Manchester United were awakened by their captain to claim the International Champions Cup crown over rival Liverpool.
Before the crowd could calm down after celebrating the first United strike, Juan Mata earned a goal after his shot deflected off of Mamadou Sakho in the 57th minute.
Rooney, who captained the side for the first time this preseason, almost put United ahead by two goals in the 65th minute on a bizarre play that saw the ball bounce off the back of the goal and back into play.
After a discussion between the fourth official and the referee, Rooney's shot into the net was correctly ruled a goal kick.
Jesse Lingard added a third goal in the 88th minute after he connected on a cross from Ashley Young in the middle of the pitch.
Liverpool's lone goal came in the 14th minute by way of a Steven Gerrard penalty that easily beat David de Gea.
Raheem Sterling earned the penalty on the left side of the box after he beat Phil Jones and was hacked down by the United defender.
The young winger could've earned a second penalty in the 33rd minute, but he was told to get up immediately by American referee Mark Geiger after making contact with the pitch.
Throughout most of the first 45 minutes, Liverpool put United under pressure with a high press and some electric play in the midfield by Sterling and Philippe Coutinho.
The only real threat posed by the United attack in the first half came in the fifth minute, when Young hit a cross in from the left for Hernandez, who couldn't connect with the ball before Sakho cleared it away.
The Red Devils were handed a bit of concern in the eighth minute, when Luke Shaw had to enter the match in place of an injured Antonio Valencia.
Despite seeing three goals fly in during the second half, neither side found a consistent attacking impetus in the final half of their respective American tours.
With the victory, United became the second winner of the International Champions Cup, which was won by Real Madrid over Chelsea in 2013.
Key Player Grades
Raheem Sterling, M, Liverpool: B
Sterling was electric in the first half against a United defense that did not know how to deal with him.
He earned a penalty in the 13th minute before coming close to earning a second one later in the half.
As the game went on, his influence dwindled, but he did hand United manager Louis van Gaal plenty of concerns about his back three.
Wayne Rooney, F, Manchester United: B+
Rooney's strike in the 55th minute gave his side a ton of momentum to go on to earn the win in Miami.
The English forward may not have had his best game on the American tour Monday night, but he did make a major impact on the final result.
Mamadou Sakho, D, Liverpool: B
The French defender disrupted any potential attacking threat that United tried to create in the first half, including his fifth-minute clearance of the cross sent in by Young.
Although he did put in a good shift before leaving the match for Kolo Toure, the deflection on the second United goal did go off of his body.
Louis van Gaal was happy with winning the tournament, but he noted that the English Premier League opener is the more important match:
The United boss was also happy to see Rooney earn the Player of the Tournament award:
Liverpool boss Brendan Rodgers was pleased with his side's efforts throughout the entire competition:
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