West Ham star Dimitri Payet should have seen red for a dive in his side's FA Cup draw against Manchester United, according to Chris Smalling.
The Frenchman had already been booked when he went down under a challenge from Marcos Rojo in the 1-1 draw at Old Trafford on Sunday.
Payet equalised with a tremendous free-kick shortly after he escaped punishment and Smalling was unhappy with referee Martin Atkinson.
"I've heard there was no contact and, to be fair, it should have been another yellow card," he said.
"But there are many decisions in a game and it's one that didn't go our way.
"I think if they're not going to give a penalty, then it has got to be diving, really, hasn't it?
"I think more often than not, if you dive you do get a yellow card. Obviously on this occasion it didn't happen but we won't pin the game on the one decision.
"But it is frustrating for us and obviously they punished us with a very good free-kick."
Smalling and United turn their attentions to Thursday's Europa League second leg against Liverpool at Old Trafford as they look to overturn a 2-0 deficit.
The 26-year-old called on his team to believe they can reach the quarter-finals.
"We can't afford any slip-ups on Thursday. We talk a lot about how to start the game and starting it strong and now we turn out attention back to Liverpool," Smalling added.
"It's now time for us to step up and give ourselves a fighting chance on Thursday by going out there and believing.
"It's not impossible. We know how crucial that first goal is going to be. If we can start well and get the crowd going then anything is possible."