Manchester United manager David Moyes rued his side's wastefulness as they drew 0-0 with bottom-of-the-group Real Sociedad in the Champions League.
Javier Hernandez missed from six yards while Robin van Persie struck the post and missed a penalty.
"When you get games like this, you need to take your chances and we missed a big opportunity to win," Moyes said.
He also defended Ashley Young after the United winger was accusing of conning the referee to win United a penalty.
Young was spoken to by former United boss Sir Alex Ferguson last year for going to ground too easily, while Moyes gave the player another warning in September following a controversial incident in which Crystal Palace's Kagisho Dikgacoi was sent off.
After the Sociedad match, former United captain Roy Keane told ITV that Young had "conned" Italian referee Nicola Rizzoli, who booked Markel Bergara for the challenge.
But Moyes said: "The boy certainly tugs him in the box.
"All I know is he got a penalty kick from a decision. I don't know anything about reputations or anything.
"If you look, the referee is two yards away from it and decided to give it."
Asked about Marouane Fellaini's sending-off, his first since joining United in the summer from Everton, Moyes added: "It was the totting up [of tackles] that got him sent off, but I thought it was harsh. I thought there were some strange decisions all night."
After a lacklustre opening period in San Sebastian, Van Persie was introduced in the 63rd minute to help boost United's attacking options and it succeeded as he hit the woodwork within minutes of replacing Wayne Rooney.
The Dutchman could not convert his penalty seven minutes later after Young was impeded.
But after Bayer Leverkusen and Shakhtar Donetsk also shared a goalless draw in Group A, United can reach the last 16 if they win their next game against Leverkusen on 27 November.
"We're still top of the group, in a good position," Moyes added.
"But that was a game we should have won. It was there for us to take the points, get ourselves in a really strong position and get clear. We've not done it, but we're capable of doing it in the other games as well."
Ryan Giggs, who made his 950th Manchester United appearance, is confident the Premier League champions will reach the knockout stages.
"If you get a point away from home and win your home games, you usually go through and we are on track to do that," the 39-year-old said.
"We will try to qualify, but we have two tough games to come. We have played Shakhtar and Leverkusen, so we know what they are all about and we are confident we can go through."