Craig Shakespeare's men made a good start to the game as Islam Slimani nodded home in the 12th minute, but Mo Salah restored parity eight minutes later with his own headed finish.
But the goal of the day went to Coutinho after hitting the sweetest of strikes to put the Reds in front and sealed there victory on the Hong Kong tournament
Although not unusual for the tricky Brazilian, he shone during the match at the Hong Kong Stadium and was directly involved in both goals that oozed with quality.
His chipped assist for Salah to score the equalising goal showed his already-acute understanding with the Egyptian while his own effort was superb - a thunderous curler that nestled in the bottom corner.
The question now is if the Reds can keep hold of their star man - his link-up play with Salah and Roberto Firmino already a hugely exciting prospect - as Barcelona continue to sniff around.
Three games in for Liverpool's £34m signing and it's looking like he could be a fine acquisition, with Salah having a hand in the two strikes on Saturday.
He scored Liverpool's first goal - taking his tally to two in three appearances - having set off the move himself, as he slid the ball across the top of the box for Coutinho's chip before racing into the space to finish it off.
He did the same just before the break as he found Firmino following a darting run across the top of the box, with the Brazilian then teeing up compatriot Coutinho for his dazzling finish.
The two vital contributions were supported by numerous tricks, flicks and crosses from the channels, although some were arguably more successful than others.
But overall, it has been a strong start from the former Chelsea winger and he will be hoping it paves the way for him to prove he can cut it in the Premier League.
