"You have to look at that season as a whole and we've had ups and downs," Horner insisted. "Karthikeyan has helped us on occasion and not on others. You have to look at the season in its entirety rather than picking out individual single moments."
Despite looking to have the faster car for much of the race, the pass when it happened had been no easy task for Hamilton.
"It was actually quite tricky," said the McLaren driver. "When I finally got close to [Seb], I seemed to be catching him in the first sector, the backmarkers came into play, finally.
"It worked out and I knew that was going to be the lap. I turned the engine up to maximise the revs. Went for the inside, but he defended. I went to the outside and he closed the door a bit so I was very lucky," he added.