Marko Grujic left frustrated during Serbia's European Under-21's opener

Liverpool midfielder ​Marko Grujic ​endured a frustrating start to the European Under-21's Championship in Poland as Serbia were beaten 2-0 by a resolute Portuguese side.

Grujic had the two best chances for his side on Saturday evening before being substituted with just over 20 minutes remaining on the clock.

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Grujic at the heart of Serbia's play from the off

The Serbian began the game in central midfield, collecting a booking early on despite a promising start to the game. Showing his physical attributes from the off, Grujic recieved a yellow card after just five minutes following his lunge on Goncalo Guedes.

The free-kick that followed almost brought about the opening goal of the game as Ruben Neves struck his volley against the woodwork - a let off for both Serbia and the Liverpool youngster.

The 21-year-old remained a bright figure in the side despite his early warning, coming close when the ball was cut back nicely to him by Milan Gajic after 13 minutes before a great block denied him the opener.

Collecting the ball in the middle of the park before roaming forward with power and purpose, Grujic spread the play out wide on countless occassions to keep the game ticking over, with Andrija Zivkovic proving to be of particular danger to the Portugese defence.

Reds midfielder left frustrated as European campaign kicks off

However, it was Portugal who took the lead. Against the run of play, Guedes headed into the back of the net after a cut-back from his teammate was plamed into the danger area by goalkeeper Vanja Milinkovic.

Grujic then had a glorious chance to level the scoring up again, meeting Zivkovic's cross from just six yards out only to direct his header wide of the goal.

A second-half substitution saw Renato Sanches enter the fray before he produced a delightful through-ball to Bruno Fernandes for Portugal's second goal to wrap up the points.

Marko Grujic departed after 67 minutes of action and despite his side succumbing to a dissapointing defeat, there was plenty to be admired from the youngsters performance. His physicality in the middle of the park could yet prove to be a valuable asset for his country in the games to come, with Macedonia next on the agenda on Tuesday night.

Despite a first season at Anfield that was largely disrupted by untimely injuries, Grujic will be eager to mount his claim for a spot in Klopp's Premier League plans next season.