[citation needed] On 13 December 2017, he scored a goal to help his team to a victory over Mohun Bagan in a crucial under-18 I-League match.

Mehtab was the worst affected as he was seen with a bloody forehead and lay unconscious for sometime before being rushed to the hospital where he had 18 stitches.

Defender Sandesh Jhingan subsequently scored his penalty for Bengaluru FC, knocking The Islanders out of the playoffs.

[20] Mehtab scored his first goal of the season against NorthEast United FC, in an eventual 1-2 away win for the club.

He remained a regular starter as the club lost the ISL Shield on the final day against Mohun Bagan Super Giant,[22] but took revenge in the ISL Cup final, where this time the club won 3-1 against Mohun Bagan Super Giant.

He scored his first goal of the season in a hard-fought 1-0 win over Hyderabad FC, heading in from a Lallianzuala Chhangte corner.

[24] On 13 February 2019, Singh was called up to the India under-23 side which participated in the 2020 AFC U-23 Championship qualifiers.

[27] He made his debut in the Hero Tri-Nation International Football Tournament against Myanmar on 22 March, as one of the starters in a 1–0 victory.