Head coach Warren Gatland believes topping their pool would give Wales a mental advantage in a Rugby World Cup quarter-final.
Wales won their opening two games beating Georgia and Australia.
They play Fiji on Wednesday before facing Uruguay on Sunday, 13 October.
"If you win the group it's a big psychological boost because you're playing a quarter-final against a team who might have lost a game in their pool," said Gatland.
"I think psychologically it's quite important for us to win this group, win the next two games, and then to start thinking about our quarter-final opponent."
Wales became favourites to win Pool D with their thrilling 29-25 victory over the Wallabies in Tokyo.
If Wales top their pool they will face the runners up of Pool C in the quarter-finals, which is likely to be England or France with Argentina now only having an outside chance of qualification.
"It was a great first half against Australia and for 20 minutes in the second half we barely touched the ball," Gatland told WRU TV.
"They came back at us and we showed some great character in the last eight or 10 minutes.
"To get that win was hugely important for us to be in control of this group and then hopefully to win it, as that would be important for us. "
Despite having already beaten their biggest rivals for the top spot, Gatland will take nothing for granted. He is pleased to have had a 10-day gap before facing Fiji.
"It's important for us to give the guys some rest and recovery, a bit of me time, and a chance to look around the place and catch up with family and friends as well," said Gatland.
"We've refreshed nicely since the Australia game and the guys are looking forward to the opportunity against Fiji.
"We'll be fresh and we've had a little training where the guys have worked on their own.
"We had an optional training session where virtually everyone did it. We had a bit of a blowout which was positive and now we're building into a normal Test week.
"The next two matches are very important. Fiji are going to be tough for us. They had a great performance against Georgia.
"They're very much a confidence side so we'll have to be on top of our game and be defensively strong at the set-piece.
"We've got a short turnaround of four days so a lot of the players who haven't had any rugby will get an opportunity then. They'll be chomping at the bit to play against Uruguay."
'Blessed' with outside-halves
Wales remain confident fly-half Dan Biggar should be "ready to go" to face Fiji in Oita.
He has returned to training after going through head injury protocols having been forced to leave the field in the win over Australia.
Attack coach Stephen Jones though is also full of praise for Rhys Patchell who took over number 10 duties against the Wallabies.
"You have got to give Rhys a huge amount of credit," said Jones.
"He has put a lot of time in with Neil Jenkins as well.
"He has worked hard on his game and it was wonderful to see that transfer to the pitch against Australia. To come on and do what he did, he deserves a huge amount of credit.
"It's brilliant. You look at the talent they both have, the mental toughness they have, it's great. We are in a fortunate position.
"I just think we're blessed. From my end, to go out on the paddock and work with those guys, when you've got a group driving each other all the time, that's what you want."
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