"We were one down and another player was drafted in from the club side, he was a fill-in. We had no subs so we played with what we had. We missed a few chances ourselves - the scoreline would have been different otherwise but it was a good game. I'm pleased with the guys."
He said Singh took "a big hit" to the temple.
"He wasn't knocked out but he couldn't go back on."
Lall, a doctor, said they would be keeping an eye on the injury to see if Singh will be able to return to the turf on Saturday.
Rotorua Aces also played at Smallbone Park on Saturday, coming out 2-1 winners over defending champions Otumoetai.
"We had to push something special out - it wasn't a game we could take lightly with their fitness and speed," said player-coach Tenga Rangitauira.
Owen Mitai-Wells scored from open play while Tuterangi Raharuhi drag-flicked from a penalty corner.
Meanwhile, the Rotorua Aces women's team had a 2-2 draw with Otumoetai at Mount Maunganui.
"It was a great game, really fair," said player Parekura Rangitauira.
"We always pick ourselves up for games like this because we know it's going to be tough. The girls played really well.
"The young ones stepped up which was great to see ... for them it's about knowing they can manage a game like that against a team of that calibre. The competition is starting to look really interesting."
Orewa Hepi and Tori Robinson scored for the Aces.