Vicario kept a clean as Spurs and Monaco played out a 0-0 draw.
Frank later said, "I think it was a game where relatively even first half and then a second half where I think Monaco was better than us, where we didn't hit the performance we want.
"I think we lacked a bit of intensity overall in the game, especially the second half. And that combined with a day where we didn't get too many players at a good enough level, that can happen.I think we are learning Champions League and every game in Champions League is difficult, especially away games against a good Monaco side, Monaco side I said, before the game, which I also think it's fair to say they had the best half of the season against us, but fair play to them and then the ability for us to compete in the Premier League and then in the Champions League is a challenge we are up for and want to.
"I also think it's fair to say last year we finished 17th and competed in Europa League, so we are taking it step by step. And it's not the worst thing on a bad day to get a point and a clean sheet. I think today the clean sheet was down to a few things, but a big thing down to Vicario, I think, that played a fantastic game."
On whether they're missing a goalscorer like Harry Kane or Heung-min Son, Frank also said: "I think that's fair to say. Wilson Odobert is a very, very good talent and I think he's been positive but of course he is taking his step into the Premier League and the Champions League.
"With other players also, Xavi (Simons) has just come to the club, Lucas (Bergvall) is a young player, (Mohammed) Kudus has been exceptional for us, but also played more or less every minute. So we lack maybe that little extra spark today.
"(Randal) Kolo Muani we believe can make a difference and look positive when he came on. But he had that injury, so of course there's some of that. No complaints, it is what it is. It's my job to get the most out of the players available."