The game's defining moment of brilliance looked to have come just before half-time as Hornets playmaker Almen Abdi converted a delightful free-kick. But with the in-form Hertfordshire outfit staring at another three points to strengthen their grip on second place, Sako popped up to convert Matt Doherty's long throw-in to make it 1-1 at Molineux.
"It's disappointing because I didn't see it coming, I thought we were in control of the game," Zola said.
"But I believe the difference wasn't the goal conceded it was the second goal we didn't score. We had opportunities. We were controlling their set-plays, something which could have been a problem because they kept putting a lot of balls forward, so because of that I thought it was finished. I didn't see it, honestly I didn't see the last goal coming.
"I was already thinking the game was won and their late goal was a shock for me as it was for all the team. But I repeat we obviously have to be more clinical when we have opportunities because 1-0 away from home is not enough."
Watford's are nothing compared to those of ailing Wolves, who still face the very real prospect of back-to-back relegations. Manager Dean Saunders, the club's fourth in 12 months, is still waiting for his first victory in charge having overseen nine of 13 winless matches. But he admitted the last-gasp point felt like more.
"It almost feels like a win," the Welshman said.
"The players are fighting and hopefully that gives them a bit of belief because we never won but it feels like we did.
"I thought we contained Watford for most of the first half. It was St David's Day so I thought I might get a bit of luck but I didn't realise their goalkeeper, (Jonathan) Bond, is Welsh as well so he had a good day. The players kept going and they've come out second half and stayed in the game.
"I knew Watford would get a few chances on the break when we tried to creep back into the game, and when Jack (Robinson) missed an open goal I thought, will we get another chance? But we did."
Source: PA
Source: PA