At a loss
Many will have expected Jose Mourinho's side to walk over Mark Hughes' side, who were wallowing in the Premier League relegation zone ahead of the clash at Old Trafford.
It certainly was that, with United bombarding the Potters with a host of chances, before Anthony Martial managed to open the scoring with his curled effort in the 69th minute. However, an effort from Joe Allen managed to share the points, and Herrera said that he isn't sure how they didn't collect the three points.
"We cannot believe we did not win this game," he told manutd.com. "I think we played even better than against Leicester as we created maybe 10 or 11 chances in front of their keeper [Lee Grant]. He was their best player and that says everything. I think our fans can be proud as we did everything and tried to win."
He continued: "If we had scored the second, we would have killed the game but we didn't."
Always a big game
Mourinho's side will face a tough test after the international break, which will start with a tough Monday night to Anfield with title contenders Liverpool, and the Spaniard reiterated the importance of the fierce clash.
"It's a big game for us," Herrera told the club's website. "For our fans - away to Liverpool. We had a good example last time when we didn't come back well after an international break and now we have a chance to fix it. We can say that. We have a chance to avoid that moment."
Herrera concluded: "We are going to try. I think it's good playing on a Monday as all our South American players have more time to recover and get back in the team. We have to keep working."
Manchester United will take on Liverpool at Anfield on Monday, October 17 with kick-off at 8pm BST.