Coutinho and Lallana were allowed to miss the start of the pre-season campaign after being called up for Brazil and England at the end of last season.
The influential pair looked happy enough as they met up with their team-mates at the club’s Melwood training centre.
Coutinho has been linked with a move away from Anfield during the summer with Paris Saint-Germain showing an interest in signing the talented star.
Liverpool have remained resolute over his future and are adamant he will not be going anywhere.
Lallana will be hoping for an injury free campaign after missing the crucial run-in last season with a thigh injury.
Jurgen Klopp now has the majority of his squad back with him with the only exception being Emre Can who will return later in July following his participation at the Confederations Cup for Germany.
Liverpool play their first pre-season game against Tranmere on Wednesday night before facing Wigan on Friday.
Both of those games will come too early for Coutinho and Lallana to feature in, but they should return to action when Liverpool travel to Hong Kong for the Premier League Asia Trophy which gets underway on July 19.
The Reds kick off the Premier League season against Watford before facing a huge Champions League qualifier the following week.