The striker was central to the action with the game in the balance midway through the second half and City 2-1 up at the Etihad.
Roberto was brought down for a penalty on 61 minutes and picked himself up to take the spot-kick only to see Joe Hart save his effort down to his right.
Just two minutes later and Roberto was there again, this time meeting Danny Rose’s low cross with a sweet strike from 14 yards that Hart kept out with his legs.
City then struck the decisive blow as Federico Fazio was sent off for a tug on Sergio Aguero, who slotted home from the penalty spot for 3-1. Aguero soon fired home his fourth and that’s how it stayed.
“It was an open game for both sides,” said Roberto. “We had chances to score in the first half and later to go on to win the game.
“In the second half we had the opportunity with my penalty to make it 2-2 but after this when Federico got the red card the game was over.
“I felt good on the pitch and my confidence was up when I went to take the penalty but the keeper saved it.
“One minute after my penalty I had another attempt with my left foot which was close but the keeper saved with his legs. It was a big opportunity for us as well but it wasn’t possible to score.
“Five minutes later Aguero scored and we got a red card and that finished the game.
"It was a good performance and we wanted the three points but it didn’t happen today.
“Now we need to forget this game ahead of Thursday and Sunday and look forward. We are producing some good performances and we need to keep this going. I am working hard and I think the goals are coming soon.”
We take on Asteras Tripolis in our third group match in the Europa League at White Hart Lane on Thursday before facing Newcastle back at the Lane on Sunday week, October 26.