The Reds suffered a setback in the first half after Nathaniel Clyne was penalised for bringing down Anthony Martial and the France international scored from the penalty spot.
However, Coutinho netted a brilliant strike to hand Liverpool a 3-1 aggregate lead and book their place in the Europa League quarter-final draw on Friday afternoon.
Firmino, who scored one of Liverpool’s goals in their first leg 2-0 win, dedicated a message to Coutinho on his Instagram page after a famous Europa League win for the Reds.
Firmino wrote: “Congratulations @phil.coutinho #golaçO #ynwa #quality”
Liverpool are in action against Southampton at St Mary’s on Sunday afternoon in the Premier League.
The Reds are in eighth place in the Premier League table and seven points behind fourth-placed Manchester City in the race to secure a place in next season’s Champions League.
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