Naby Keita and Roberto Firmino struck inside the first 26 minutes on Tuesday night.
"2-0 is a really good result," said Liverpool boss Jurgen Klopp. "I would have taken it before the game and I take it now."
Liverpool, who lead the English Premier League, are chasing a first English league title in 29 years.
They host third-placed Chelsea on 14 April before the second leg of the Champions League quarter-final at the Estadio do Dragao on 17 April.
"It was a good game, a controlled game," added Klopp. "We deserved the win 100 percent and scored two wonderful goals."
Despite the advantage, Klopp said his players will need to maintain their poise in Porto.
"We have to go there and we have to fight," he added. "Porto will do everything to strike back but that's how it should be in the Champions League quarter-finals."