Mentz laments 'slipped' chances
The loss was the Pumas third in a row and they are currently in eighth position on the standings. They are still without a win in this year's Currie Cup Premier Division.
"We played much better rugby at times tonight [Friday]," said Mentz.
"Unfortunately, we slipped two easy tries that they converted. We scored our four tries that we were really happy about and we really competed well in set pieces, but it was still not good enough on the night.
"The slipped chances were really disappointing."
Meanwhile, Griquas head coach Peter Engledow said he was happy with the win, despite his team not being at their best throughout the 80 minutes.
"We are delighted to get the win," said Engledow.
"Obviously we came a here [Nelspruit] a few times before and came unstuck. We knew it was going to be a very intense battle and we knew the Pumas were under quite a bit of pressure, so they came out hard.
"I am just delighted with the performance. We were not at our best, but the guys held out and it was a good battle."