Downing gave the visitors a second-minute lead when he nodded past Ali Al-Habsi after superb work on the wing from Philippe Coutinho.
The Brazilian was central to Liverpool’s second as his slick pass allowed Suárez to race clear of Wigan’s defence and fire low past the Latics goalkeeper.
The Uruguay international then became the Premier League’s top scorer when his free-kick crept past Al-Habsi before half-time – and the 26-year-old netted his third – and 21st of the campaign – in the 48th minute to seal three points.
“He must be a nightmare for defender,” said Downing.
“He can be quiet in games but you’ve got be on your toes at all times because he can score anything out of nothing.
“You’ve seen his goals today are top quality finishes and he’s been brilliant for us all season. He’s a top player.”
Reina added: “He can make a goal from nothing. He can score different kind of goals and he can create chances for himself and give assists for other team-mates. He’s been brilliant so far.”
The win moves Liverpool up to seventh place in the Premier League table, while Wigan remain just above the relegation zone on goal difference.