Former Liverpool and Chelsea striker Torres opened the scoring at Camp Nou in the first half, before picking up two yellow cards in quick succession for fouls on Neymar and Sergio Busquets before the break.
Suarez scored twice in the second half to secure a victory for the holders, giving them a slight advantage ahead of the second leg of the quarter-final at the Vicente Calderon, and the Uruguay international said the sending-off proved to be key.
"It was decisive because everyone knows the quality player Fernando is," he told TV3. "He made two heavy fouls. It was a shame because it would have been good to have 11 against 11.
"Knowing that it would be a difficult game, we could have scored another, but they have to now get a goal there [in the second leg]."
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Atletico boss Diego Simeone was left incensed on the sidelines when Busquets escaped a booking for a late lunge shortly after Torres' dismissal, and the game proved to be ill-tempered throughout, with the visitors issued eight bookings in total to Barca's three.
Suarez was also fortunate to escape punishment for a petulant kick out at Juanfran during the first half, but Barca technical director Robert Fernandez insisted afterwards that Atleti could have seen more players sent off in the second period.
"The referee has harmed both of us," he said. "A number of Atletico players deserved one more card. It was a difficult game to referee.
"The first goal calmed us down and gave us strength to look for the win. We knew it would be a very close game."