Doak arrived at Liverpool carrying injuries, a series of back, groin and ankle issues which medics believed were linked to growth, and so was eased into action with Marc Bridge-Wilkinson's U18 side during pre-season.
But it wasn't long before he was making his presence felt. His debut came in a 3-2 friendly win away to Cardiff in July, and a week later he netted his first goal as Leicester were battered 6-1 at Kirkby.
Once the season proper got underway, Doak continued his fine form. He scored twice in Liverpool's first U18 Premier League game, a 6-2 thrashing of Middlesbrough, and again in a narrow defeat to Leeds the following week.
By September, he had been drafted into the U19s for their UEFA Youth League campaign, and he opened his account in that competition with a goal and an assist as Napoli were beaten 2-1 in Italy.
A standout moment came in October, when he scored a remarkable winner away at Rangers, retrieving the ball near the corner flag before dribbling his way past four opponents into the penalty area and finishing with the outside of his right foot. Scores of friends and family were in Partick Thistle's Firhill Stadium to witness it, and Doak celebrated accordingly, although he chose, wisely, not to attend that evening's Champions League clash at Ibrox, on account of his Celtic connections.
Doak finished with four goals from six Youth League appearances, and continued to score and assist regularly for the U18s. He also netted for Barry Lewtas' U21 side against League One outfit Accrington Stanley in the Papa John's Trophy in October, and when the Reds faced Derby County in the third round of the Carabao Cup in early November, he was drafted into Klopp's senior squad.
He performed well, thrilling fans with a positive, nerveless display after replacing Fabio Carvalho 16 minutes from the end of a goalless draw (Liverpool won on penalties), and with the domestic season breaking soon after for the World Cup, he joined the Reds first-team on their 10-day training camp in Dubai in December, catching the eye by setting up a goal for Darwin Nunez in a friendly win over AC Milan.
Since the resumption of club football, Doak has remained in and around Liverpool's first team. A lively cameo off the bench at Aston Villa on Boxing Day, in which he tormented the former Everton left-back Lucas Digne, had Klopp smiling. "That's Ben!" he told his post-match press conference, and the youngster was similarly impressive in a six-minute run out against Wolves at Anfield in the FA Cup, before being handed a 22-minute appearance in the league defeat to Brighton.