The Wales wing struck six minutes from time though a 50-metre individual effort
The Wales wing struck six minutes from time though a 50-metre individual effort that saw him outpace Fiji’s defensive cover and turn a tight, tense contest Wales’ way.
“That’s what he can do,” Pivac said. “You can’t coach that. It is express pace.
“I was pleased for him. He was marked fairly heavily, and I was really pleased that he showed individual brilliance and the raw pace that he has. It’s great to have him in your side.”
Wales survived a major fright against 14-man Fiji before claiming their first victory of the Autumn Nations Series.
Fiji had wing Eroni Sau sent off and two players sin-binned, but Wales found it tough going until wing Alex Cuthbert marked his first Test appearance for four years with a crucial try 13 minutes from time and Rees-Zammit then took centre-stage.
Hooker Ryan Elias touched down twice, and there were also tries for scrum-half Kieran Hardy and full-back Liam Williams, with Dan Biggar and Callum Sheedy each kicking two conversions.
Pivac added: “It was probably everything you would expect in a Wales-Fiji game. Everything we talked about before the game pretty much came to fruition.
“There was a lot of off-loading going on in the early part of the game, and we talked about being accurate defensively.
“The biggest problem for us in the first 60 minutes was the fact we had separation at the breakdown.
“They were very strong over the ball, and we talked about that all week along. That’s a concern, and it is something we will be working very hard on this week.”
Asked about Fiji’s red card and two yellows, Pivac said: “I don’t think you can put the cart before the horse and worry about what it does to the game.
“Any team that infringes in that way in your 22, you are going to get a card, and unfortunately for Fiji, that happened today.”
Prop WillGriff John and lock Will Rowlands suffered head knocks – John went off just seven minutes into his first Test start – while Josh Adams who was due to start at outside centre, was withdrawn just before kick-off.
Wales conclude their autumn Tests by hosting Australia next weekend, and Pivac said: “Josh just felt something in his leg in the warm-up.
“He wanted to start the game and see how it went, but we certainly weren’t going to allow that to happen. He was concerned about letting his team-mates down.
“We had a couple of head knocks – WillGriff John and Will Rowlands. With a six-day turnaround, we will just have to see how they are tomorrow. It could be that we dig a bit deeper into the squad. We would have to say they are in doubt.”
Reflecting on the game, Pivac added: “Fiji were very physical, and at times we were knocked off our stride. It’s as simple as that.
“Fiji are so big and strong over the ball, guys who can get over the ball and are strong over it. They didn’t let us down in that area, and you have got to give credit to the opposition.
“Fiji threw everything as us. They went down a man, and that galvanised them.”
Fidji, almost triumphed over adversity after Sau was red-carded for a dangerous tackle on Wales centre Johnny Williams after 25 minute.
Captain Waisea Nayacalevu scored two tries – his second score being a spectacular team try – while fly-half Ben Volavola kicked 13 points and they led 23-14 after an hour.
Fiji head coach Gareth Baber said: “There is a way of playing the game. We play it physical, but you’ve got to have control.
“Cards hurt teams, and particularly playing against a team like Wales, you get three in a game and you are probably looking at a loss.
“We hassled Wales and didn’t let them settle on the game that they wanted to play. We were physical in everything we did.
“I am immensely proud of a group of players who really only came together 10 days ago.”