Chicharito admitted he had never been involved in such a "crazy match" after Sir Alex's last game in charge ended in a 5-5 draw with West Brom at The Hawthorns.
The Mexican striker netted United's fifth goal and afterwards spoke of his gratitude for the boss and his respect for Paul Scholes who also retired on Sunday.
"The impact Sir Alex has had on me is massive. He gave me this big chance to play at the biggest club in the world. He has taught me a lot and I only have thankful words for him," he told MUTV.
"It [Sir Alex's retirement] is not only a loss for the British fans but he has changed football across the world. He has been here for 26 years and made the impossible dream come true.
"And what can I say about Paul Scholes? All the players say the same thing about him - he's an incredible player and team-mate, and the class and talent he has is unbelievable."
Chicharito's second half strike was his 50th goal for the Reds. It's a landmark he is proud of but he was keen to reiterate that team achievements come before personal ones.
"I'm very pleased to have 50 goals but the most important thing is I have won two league titles in three years and played in the Champions League final. Like I always say the most important thing is the team and to help the team win trophies," he added.