Di Maria performed in front of the Old Trafford crowd for the first time since completing a British-record transfer of £59.7 million from Real Madrid last month and he put in a man-of-the-match display against Harry Redknapp's men on Sunday.
The Argentina international scored the opening goal and had a hand in the other three from Herrera, Wayne Rooney and Juan Mata.
Spain international midfielder Mata praised the performance of his team-mate and stated that Di Maria has fitted in superbly at United.
"It seems [like] he's been with us for a long time," Mata posted on his personal blog.
"Angel is a very enthusiastic guy, a great signing. After the game I gave to him the MVP [man of the match] trophy and improvised as his translator for the TV.
"He looks happy and that makes us happy as well."
Herrera, whose goal was his first since joining from Athletic Bilbao, was equally glowing in his appraisal and suggested that Di Maria is among the world's best players.
"Angel is one of the best players in the world," he told United's official website. "Manchester United always has to have top players and he is one of the best."
Radamel Falcao came off the bench to make his United bow, while Marcos Rojo and Daley Blind also made their debuts and fellow new boy Luke Shaw was among the substitutes.
And Herrera believes that Louis van Gaal's side are showing signs of improvement with the recruits now on board.
"We have Radamel Falcao as well, [also] Daley Blind, Marcos Rojo and Luke Shaw," he added. "I think we have a new team but we are improving, we are working hard and we are looking forward to this season."
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