Verstappen produced an incredible recovery drive to record Red Bull's first race win since October 2018, when the Dutchman won in Mexico.
The Red Bull man showed some remarkable speed when going past the likes of Sebastian Vettel and Valtteri Bottas with relative ease, before eventually overtaking the fastest car of the weekend with Charles Leclerc's Ferrari.
Horner was left confused and unsure how to explain it, when speaking to Motorsport.com: "In the second half of the race, we were really on fire. The car was incredibly quick. The reality is that we don't fully understand why.
"Obviously the updates we have been bringing to the car over the last couple of races have started to come together and work very well, but this race was won the hard way. We had to go and pass three of the four main opposition and Max did just that."