Havelock looked to have clinched the win when they made it 4-1 following a goal mouth scramble.
“The boys refused to throw in the towel and they continued to make a fight of it,” Robertson said.
“Nicky Land got us back in the game with well-taken goal and then with five minutes to go Corey Adams scored from a free-kick.”
Robertson was forced to reshuffle his team before the kick-off when Ander Batarrita injured his lower back in the warm-up.
Malcolm Marfell, who was initially in the reserves after Josh Adams passed a late fitness test on an injured ankle, replaced Batarrita.
“We didn’t think Josh would be fit but he’s young and his ankle cleared up in time for him to start, but now he’s got a hip injury.”
Goodlett is also on the casualty list with a groin strain which saw him replaced by Mark Baple in the second half. Thistle went into the cup tie having beaten Havelock North Wanderers 3-1 in a Central Federation League game in Gisborne two weeks ago but Robertson said they obviously learned their lesson from that defeat.
“They were a lot more physical, especially in midfield. They really got stuck into us, played cup football. On the positive side, we can now focus fully on the league , starting with Port Hill United here on Saturday.
“We beat them 1-0 away in the first game of the season so we’ll be looking for another good result this weekend.
“It’s important we forget about this loss and bounce back this weekend.”