Rotorua deserve credit for taking the game to Taupo after the break, and with an ounce of luck could have been back on level terms. But Taupo woke from their half-time slumbers and normal transmission was resumed.
Lamb was given space in the box and coolly picked his spot to complete the scoring.
At Rex Morpeth Park, Whakatane Town found themselves 1-0 down against Otorohanga at the break but after an early second-half goal the floodgates opened and they ran out convincing 6-1 winners. Brendan Mitchell netted a hat-trick, with Sean Henderson, Wade Malony and Scott Marrow also scoring.
Otumoetai were ahead 3-0 against Ngongotaha at halftime but the Villagers played with more purpose after the break.
After scoring twice they were unlucky not to at least share the points.
Keeper Graeme Blisset hit the wood work and a referring decision that ruled out what looked to be a legitimate goal conspired to give Otumoetai a 3-2 win.
Matt Collins (2) and Andrew Gibbs scored for Otumoetai.
Old Blues were left lamenting two missed penalties when they were beaten 3-2 by AFC Fury.
The referee awarded four penalties in total with Fury taking the lead when they scored from the spot in the first half.
An Andy Carter penalty and a goal from Tim Clark had Old Blues ahead with 15 minutes to play but the inexperienced side couldn't close the game out.
"Fury played well but the game was there for the taking," Old Blues coach Andy Legget said.
Tauranga Boys' College with goals from Ahamed Zammit and Jack Chaney had a good 2-1 win over Melville United at Gower Park while a 1-0 against an under strength Waikato Unicol kept Claudelands in second place.