The 17-year-old was seen holding his head following a collision with Sporting defender Joao Muniz just six minutes into the tie, before stumbling and falling to the floor.
Liverpool medics rushed on to attend to the youngster, where they remained for around two minutes. Fortunately Doak returned to his feet, but the extent of his head injury prevented him playing any further part, as he was forced into an early substitution.
Liverpool gave an update on Doak's injury following the incident, stating: “Ben reported feeling dizzy on the pitch but passed all pitchside assessments and was able to walk off.
“He was as on the pitch at the end with the team and is now on the coach back to the airport. Ben is feeling well now but we are following standard FA concussion protocol.”
A natural right winger hailing from Dalry, Scotland, Doak signed from Celtic in the summer and is highly regarded as one of Liverpool's future stars.
The 17-year-old has posted four goals and four assists in seven matches in the UEFA Youth League alone, helping the Reds to reach Tuesday's quarter-final meeting with Sporting.
Beyond featuring for the Reds at youth level, Doak has also made five appearances across the Premier League, FA Cup and League Cup under Jurgen Klopp this campaign, all of which have come from the bench.
Liverpool went on to lose Tuesday's matchup against Sporting 1-0, meaning they were eliminated at the last-eight stage.
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