The LaLiga leaders produced a subdued performance in the first-leg tie but still managed to walk away with a three-goal advantage after own goals from Danielle De Rossi and Kostas Manolas handed them a 2-0 lead.
It marked the fifth own-goal in the Champions League in favour of the Champions League this season, which essentially represents the second top-scorer behind Lionel Messi's six.
Pique and Luis Suarez scored on either side of Edin Dzeko's consolation for the Serie A outfit and the Blaugrana insist their performance warranted the scoreline.
"It is not luck," said Pique in response to the own goals, as quoted by Marca. "We have hit the post several times [this season]."If there are own goals, it is because we are suffocating them with the ball being more in their area than ours."
Valverde reiterated the comments of the Spain international while mentioning the away goal conceded has kept the Giallorossi in the tie.
"If you don't get close to the goal, you don't get goals," Valverde said. "It doesn't matter if they're own goals, what are we supposed to do?
"I preferred 3-0 to 4-1, nothing is done."