The 45-year-old secured his first point as a manager in the Premier League, but it could have been more had Conor Gallagher taken a first-half chance where he hit both the post and crossbar, while Christian Benteke and James McArthur went close after the break.
New boys Brentford also had their chances, with Ivan Toney wasteful and Bryan Mbeumo striking the crossbar towards the end of the opening 45 as the London clubs played out a stalemate which helped Palace bounce back to a degree from their 3-0 loss at Chelsea last weekend.
“I have a mixed feeling because in one way I was quite pleased with the team performance but I’m frustrated that we didn’t score,” Vieira said.
“This is a side of the game we need to improve. We need more players inside the box because at times Christian was isolated.
“If we had players around him it would be a bit easier for him, so this is one side we need to work on. But when we look at the way we approached the game, the way we played with intensity and to get out of their pressure, the performance was positive.”
Selhurst Park was full for the first time since the coronavirus pandemic started and Vieira was greeted onto the pitch by huge applause, which was replicated at full-time too.
“The atmosphere was unbelievable. From the first minute the fans were behind the team and we really wanted to get the win. With a little bit more luck, maybe we score a couple of goals,” the new Eagles boss admitted.
“We have an identity and we try to build a philosophy of playing, but at times you can’t play because the opposition don’t let you. The thing I was really pleased with was the concentration and positive attitude from the players on the field.
“With the support of the fans, they tried to win and obviously we didn’t score, so we need to get more people in the box to try and score some goals.
“But if you look at Chelsea, we improve the performance and now we must keep working because there are still elements we can improve.
“I am really happy with the way the players are training and working and that performance must be the benchmark for us to improve and win football matches.”
Bees manager Thomas Frank had enjoyed a dream start to life in the top flight with an opening-day win over Arsenal and was pleased his team backed it up on the road, but he knew they could have left south London with more.
He said: “Yes I am enjoying it. I hope it will continue. It is a fantastic stage to be at and performing.
“I am really pleased and proud of how the boys presented themselves on the pitch. Just slightly disappointed with how we were on the ball.
“In a relatively even game I felt we edged it, and if we took the three points and won 1-0 you couldn’t say anything, so I am sitting here slightly disappointed.
“I think the press was really good, either high or middle and aggressive, so winning the ball a lot of times. But after we won it, we didn’t have enough quality or coolness to win the big chances.
“On the ball we need to be more cool and composed. Defensively we gave only one big chance away to Gallagher and kept (Wilfried) Zaha and Benteke quiet, so that was good.”