Bruno Fernandes was relieved to beat West Brom but knows Manchester United must do much better moving forwards.
Having started the Premier League campaign with four winless matches at Old Trafford, Ole Gunnar Solskjaer's men finally tasted victory on home soil on Saturday evening.
Fernandes was involved in penalty drama at both ends against Slaven Bilic's Baggies, with his second-half spot-kick enough to seal a narrow 1-0 win against the promoted visitors.
"It was a tough game," the Portuguese midfielder said. "They played really good football – they are tough in the back, they are strong.
"I think we can do much better in the final third. We need to do much better. I think everyone feels the same.
"The performance was good, but I think we can do much better and everyone agrees with this.
"I don't think we have to build from here. We are building from the beginning. You build from the losses also. Of course, you don't want to lose – a team like this, a club like this, doesn't need to lose to build something important.
"But it's there. We did the mistakes, and now the point is to keep going and doing the right things and, most important, take the three points."
Fernandes was twice saved by the intervention of the video assistant referee.
The 26-year-old gave away a penalty at the start of the second half, only for referee David Coote to overturn his decision after being advised to watch back the challenge on Conor Gallagher.
Fernandes swiftly had his own chance from the spot after Darnell Furlong handled, but former United goalkeeper Sam Johnstone denied him with a fine save.
However, the VAR ordered the penalty to be retaken as the West Brom goalkeeper had strayed off his line and the midfielder made no mistake with his second effort.
"I have to score," Fernandes told MUTV. "If he comes out of his line or not, for me, it doesn't matter. I have to score. I have to have one chance and put the ball in.
"I take the second chance and I'm not happy, at all, because you can't have two chances, maybe sometimes. Today you have, but maybe other times you will not have this kind of situation.
"But this happens against us in the home game against Crystal Palace when David (De Gea) saved, and after they score, so I think the rules are there."
Johnstone was frustrated by the retaken penalty and the fact the Baggies again came away with nothing, with West Brom having failed to win any of their opening nine league matches for the first time since 1985-86.
"We played well," the former United goalkeeper said. "The lads are gutted and we were under pressure for some of the game, but still created good chances.
"I made a few saves and to not even get a point is really frustrating but hopefully we can take the work-rate from the Tottenham game, tonight and then hopefully the results start swaying our way.
"You don't really want to face one penalty, two is frustrating but it's a new rule so it's difficult.
"We rode our luck at times but we hit the crossbar, had a couple of good chances and I think a point would've been fair."