Luke Shaw says "it is only a matter of time" until Manchester United thrive again after signing a new five-year deal worth a reported £150,000 a week.
The 23-year-old's current contract was set to expire next summer, with poor form and injury limiting him to 75 appearances for the club.
Shaw admits a new deal looked "impossible" at times in the last year.
However, the left-back has been a regular this season with his form prompting an international recall.
"I can't wait to continue my progress under Jose Mourinho," Shaw said.
"I personally think it's only a matter of time until the success is going to be coming back.
"We have an amazing group of players and the talent we have is scary. There are a lot of young lads that are hungry for trophies."
The England defender joined United for £27m in 2014 after establishing himself as one of the most promising full-backs in the Premier League at Southampton.
But after struggling to prove himself under former manager Louis van Gaal, he was sidelined for the majority of the 2015-16 season after breaking his leg in two places during a 2-1 defeat to PSV Eindhoven in the Champions League.
Shaw has also previously faced public criticism from current boss Jose Mourinho but has become his first choice left-back this term with a run of fine displays.
"Luke fully deserves this contract," said Mourinho, adding he "has worked really hard at every level" and "always believes in himself".
He said: "I am delighted that we are keeping such a talented young English player with a bright future ahead of him."