Mateta, Sarr and their fellow forward Evann Guessand particularly excelled, barely giving the Fiorentina defence time to settle, amidst a wonderful Selhurst Park atmosphere.
And Richards was quick to praise the efforts of the Eagles' attack.
"Those guys up top, they make our job easy," he added. "Whenever they get on the ball, they always create some sort of magic.
"And we only scored three today, but I think it could have been a lot more, so kudos to them.
"I know that in the next leg we're going to get a few more."
The USA international, who captained his country during the recent international break, also wanted to emphasise the key role Oliver Glasner has played in changing the mentality of the the club, with the Eagles now chasing a third major trophy in the space of 12 months.
"The number one thing that he's instilled since he came in is that he wants to kind of change the mentality of Palace," he said.
"He wants to make this a club that wins trophies and I think even with the people that he brought, not just staff, but players as well, it's just changed the mentality.
"We're all kind of 'drinking the Kool-Aid' like we say back home. So we want to win more trophies and that's exactly what we plan on doing."