The 17-year-old striker, promoted from the Terrors’ youth team this season, started his first game against Corinthian Casuals with Frankie Sawyer sidelined with a hamstring injury.
And he proved a more than adequate replacement as he smashed in three goals in a 5-1 romp.
“He was involved in pre-season and has impressed, so we felt he deserved his opportunity,” said Tanner, who re-signed Jordan Wilson and Troy Williams last week.
“He is a little, speedy striker and has everything you don’t want as a centre back. He is right footed, but scored his hat-trick with his left foot – one from 25 yards, one a run in behind the defence and the other a tap in.
“He definitely has a big future and we have to make sure we protect him and develop him as much as we can.”
While Nkomo was grabbing the headlines up front, Tanner also had special praise for centre back Aaron Dalhouse.
“We have had a few changes but the players that have come in have done well, particularly Aaron,” he added.
“He came on for the second half against Walton Casuals and played the whole 90 minutes on Monday and I think him and Colin Hartburn can make a really good centre-back partnership.”
Once a Terror, always a Terror: Jordan Wilson has re-signed for Tooting & Mitcham United SP63576
Having drawn 2-2 with Peacehaven & Telscombe last Wednesday and lost 3-2 to Walton Casuals on Saturday, a first league victory on Monday – which included two goals for Sol Pinnock, taking him to four for the season – was relief for Tanner.
Meanwhile, Tanner had to watch from the sidelines last year as his then team-mates Met Police made it to the first round proper of the FA Cup – a journey he would like to make with the Terrors this season, starting at Leatherhead on Saturday.
“It was good to get that win before the cup,” he said.
“Now we just need to go out there and do exactly what we did on Monday.”