Mata got on the scoresheet as United continued their recent revival after an indifferent start to the campaign, and in spite of a lengthy injury list, by overcoming Stoke 2-1 on Tuesday.
The victory was United's fourth in succession in the Barclays Premier League and maintained their position in the top four.
The second win in that sequence was a hard-fought 2-0 success at Arsenal and Mata feels things have started to build from there.
"It was very important to win at Arsenal and then to get two wins in a row at home," said Mata, also looking back to Saturday's convincing 3-0 defeat of Hull.
"Now we have the chance to have a great December - probably the most important month in the league because we play more (games)."
The Stoke clash was actually United's first home night game of the season, a notable fixture quirk that also highlights their lack of European football this term.
The gap between fixtures shrinks now, though, with six more games to be played up to and including New Year's Day.
United will be tested at third-placed Southampton next Monday and then by Liverpool the following weekend, but Mata believes the team spirit, much maligned last season, is now starting to shine through.
The 26-year-old Spaniard said: "The spirit is there
We have not been lucky with injuries, we've had important players that could not play, but the spirit is there.
"Everyone was very happy in the dressing room after the game because it was a difficult game and we showed character."
United went ahead against the Potters as Marouane Fellaini continued his recent good spell of form by heading home midway through the first half.
Stoke responded with a fine strike from Steven Nzonzi, but United claimed a decisive lead when Mata's 59th-minute free-kick from the right appeared to bounce straight in, although Marcos Rojo claimed to have got a touch.
United had the better of the play, but their performance was still not entirely convincing and Stoke three times went close to snatching an equaliser in a breathless injury-time spell.
First David de Gea produced a brilliant reflex save to keep out a Mame Biram Diouf header
He then denied Marko Arnautovic from point-blank range and the rebound attempt from Diouf was hacked off the line by Ashley Young.
The goal decision system showed the ball was roughly two thirds over the line before Young cleared or, as Stoke boss Mark Hughes put it, a "hair's breadth" away from going in.
Mata said: "It was very tough and we were, until the last minute, suffering. They played good in their way. They came here as a very compact team and they play good counter-attacks.
"At the end, it's a very important win, a fourth win in a row and we are getting closer."
It was the second time in two games United had seen the benefits of goalline technology, with defender Chris Smalling awarded a goal in another close call on Saturday.
Young said: "The referee was there with his watch and as soon as the ball hit my foot and was cleared off the line I looked to see if he was whistling for a goal.
"He wasn't and we managed to hold on to the win, so thank God for goalline technology."
Nzonzi was at a loss to explain how he ended up on the losing side after such a frantic ending.
The Frenchman, who found the net with a powerful drive from 20 yards, told the Potters' website, www.stokecityfc.com: "We're very unlucky. I don't know what to say.
"In the second half they played better, but we had some good chances a the end of the game. I don't know how we didn't score them. It's crazy. They have a really good goalkeeper, but it's unlucky.
"It's really disappointing. We could have come here and got a point but we lost. We are going to have to work really hard on Saturday against Arsenal."
Source: PA