However, the hosts fought back after the break with Tobin Heath and Kirsty Hanson both on target to ensure the points were shared.
Ironically, the two sides lock horns again at Leigh this Thursday in our latest Continental Cup group game.
But as she both reflected back to Saturday and looked ahead to this week’s re-match and beyond, USA World Cup winner Mewis believed there were many reasons for optimism.
"We have a lot of positives to draw from the game and we get to go again on Thursday,” the midfielder asserted.
"At the end of the game, we talked about continuing to stick to our principles throughout the game.
"What we were doing in the first half was working so we just needed more patience and discipline to stick to the game we know how to play.
"It was definitely a game of two halves.
"We came out really strong in the first half and score two goals and United did well to fight back.
"We're disappointed we didn't keep the lead but they're a great team and it's a great rivalry.
"I do give United credit. They did a great job in fighting back to score so it was testament to the Derby and the rivalry.
"I'm definitely feeling the animosity - I was definitely fighting back at the end and I really had a feeling of pride for City.
"We wanted to win and I'm looking forward to Thursday for another opportunity to try and beat them.”
Saturday’s result extended City’s unbeaten run to five games, an impressive sequence of results which included this month’s FA Cup final triumph over Everton.
With City also contesting the league, Continental Cup and with the onset of both the 2021 FA Cup and Champions League also on the horizon, there is still a plethora of prospective silverware on offer.
And the American – who has made a superb start to her City career – believes there is huge scope for further progress and improvement within the squad.
"We're still growing, and we have so much potential as a group,” Mewis insisted
"Every game is a learning opportunity for us, and we've taken some momentum from the FA Cup.
"Last week, a lot of players got to play, which brought us closer and more on the same page.
"We've been able to showcase the depth of the team and how many players we have who are capable of playing at a high level.
"We still have a lot to prove and work for this season."