O'Neill believes the arrival of fellow American Brad Guzan at the start of last season has brought the best out of 38-year-old Friedel.
"I think he has been reinvigorated with the arrival of young Brad Guzan," O'Neill said. "The two Americans coming together, there's a bit of competition and I just think that Brad has been exceptional. In the last number of weeks his performances have been terrific."
With Liverpool defeating Everton earlier in the day, the point means Spurs slip out of the top four and Villa remain within striking distance.
"It keeps us alive," O'Neill added. "I'm delighted with the effort because we have a team going week in and week out, and we showed great tenacity. It was probably was our best defensive performance of the season, given the opposition.
"I've had fine defenders in my time, at Leicester and Celtic, with the same mentality as these guys - willing to throw themselves everywhere."
Friedel said: "Tottenham are a very good team going forward, we saw that from the videos we watched before the game and playing against them down the years," said Friedel.
"Harry (Redknapp) has got them going, especially at home with their waves of attacks. Maybe they had the better of the chances and will be disappointed but we were strong."
He added: "We want to get as many points as possible and get in that top four if at all possible. We'll strive for that."
Spurs boss Harry Redknapp expects plenty more twists and turns before the end of the season in the race for fourth place.
He said: "Obviously it was a big result for Liverpool. They ground out a result. It's their weekend this week, it will be somebody else's next week, somebody else's the week after.
"Of course it's going to be tight, it's going to go all the way to the wire. You didn't see Manchester City getting beat at Hull, not many people would have tipped that one, would they?"