Not for the first time this year, De Gea put in an outstanding display at Old Trafford to help United record a 3-0 win over Liverpool on Sunday.
The man of the match saved two close-range efforts from Raheem Sterling and also tipped Mario Balotelli's fierce shot on to the bar in the second half of the Barclays Premier League encounter.
The 24-year-old won United all three points against Everton earlier this season with two stunning late saves and he also played a key role in the team's triumph over Southampton last Monday.
Mata has been impressed by De Gea's form this season, but he would prefer it if his compatriot was not so busy.
"We won, among other things, thanks to the 'Man of the Match' David de Gea, who has had yet another great performance," the United midfielder wrote on his blog.
"He is in top form
Everybody's praising him and now we have to keep working so we don't need so many saves from him in the next few games; we have to get better in that regard."
Many questioned Sir Alex Ferguson's decision to sign De Gea in 2011 after he made a number of costly errors in his first season.
But he is now regarded as one of the best goalkeepers in the world alongside the likes of Manuel Neuer, Joe Hart and Thibaut Courtois.
"It's tough to find anyone better than him," Mata added.
"He's been in top form since the beginning of the season and has saved a lot of points for us.
"David gives us complete confidence
Liverpool created chances and they didn't score because of him."
The reflex save to nudge Balotelli's powerful volley on to the woodwork from point-blank range was impressive, but the pick of De Gea's saves came in the second half when he denied Sterling.
Sterling picked up on a short backpass from Jonny Evans and attempted to round De Gea, but the Spaniard remained on his feet and jockeyed the England winger wide, forcing him into a weak shot.
Former United defender Rio Ferdinand believes the former Atletico Madrid man has a psychological edge over any opponent who runs at him.
"He is in imperious form," said Ferdinand, who played 455 times over 12 years at United.
"He dictated to the striker in one-on-one's and now looks like he is in strikers' heads if he faces them.
"The way he trains is now being reflected in his performances.
"Dedicated hard work and an unbelievable confidence in his ability as a keeper
Greats traits."
De Gea's progress has not gone unnoticed by Real Madrid, who are interested in signing him as a long-term replacement for Iker Casillas.
United, however, hope the player will sign an extension to his current contract, which expires in 18 months' time.
Mata, meanwhile, is refusing to get carried away despite a sixth successive win, which keeps United in third place, eight points behind leaders Chelsea.
"The team has to keep working as we did in the last few weeks," said Mata, who scored the second goal on Sunday.
"That's why we are improving
In just a few days we play against Aston Villa in a stadium with a very good atmosphere, where winning is always tough, and right after that we will be in Christmas.
"We have to maintain this positive streak and try to get as many points as possible this month."
Mata acknowledged he was offside when he nodded in United's second after a Robin van Persie flick-on.
"I was fortunate to score again," said the former Chelsea man, who has scored five times this season despite not being a regular starter.
"To be honest, I watched the footage and it's true that I'm offside after Robin's header
That is something you don't realise when you are on the pitch."
Source : PA
Source: PA