Ole Gunnar Solskjaer bemoaned his team's lack of composure in front of goal after Patrick van Aanholt's injury-time finish at Old Trafford earned Crystal Palace their first ever Premier League win over Manchester United on Saturday.
Jordan Ayew gave Palace the lead in the 32nd minute and it wasn't until Marcus Rashford's long range effort in the 58th minute that United had their first shot on target.
Rashford had the chance to equalise in the 70th minute from the penalty spot, but the England striker saw his effort cannon off the post. Daniel James levelled for United in the 89th minute with a fine curling finish, but the hosts' hopes of grabbing a late winner were dashed by Van Aanholt in the third minute of added time when the full-back's low shot squeezed past goalkeeper David de Gea.
"We just were not clinical enough in front of goal and they scored two very easy goals," Solskjaer said. "I thought we got our act together in the second half, we just couldn’t hit the target. We have dominated the game but we have not controlled it.
"We should have dealt with the last five minutes better. We defended poorly at times today and it cost us. Sometimes you do not find that end product and that happened today. We did not test their keeper enough. It cost us dearly today."
Palace defender Gary Cahill said he was proud of the way Palace responded to United's late equaliser and revealed the team were always confident of taking something from the game.
"It was a fantastic result, we had to dig in, we had to go hard," the former Chelsea captain said. "We did that and the counter at the end was fantastic. We needed a reaction after the game. We worked very hard, we had a bit of luck with the penalty miss but I think we deserve it."
West Ham United picked up their first win of the season while consigning Watford to their third successive defeat with a 3-1 victory at Vicarage Road.
Hammers captain Mark Noble gave the visitors the lead with a third minute penalty, only for Andre Gray to level 14 minutes later. However, two second-half goals from West Ham's record signing, Sebastien Haller, gave Manuel Pellegrini's side all three points.
"It's really important to get a win," Haller said. "It was time to win a game to launch the season. Now it's done, we're really happy with the result and the work from the boys.
"Watford are a really good team offensively but we tried to be patient and wait for the good moments. That is what we did. The end of the game was really tough for both teams but we played strong."
A stunning goal from Harvey Barnes and a first-half strike from Jamie Vardy, either side of Oliver McBurnie's equaliser, led Leicester City to their first win of the season, a 2-1 victory over promoted Sheffield United at Bramall Lane.
"It was tough in them conditions, especially here where the atmosphere they create is amazing," Leicester midfielder Hamza Choudhury said. "It is fine margins that wins games but luckily today Harvey Barnes put it away nicely."
Southampton also got their first win of the campaign with a 2-0 victory at 1-man Brighton & Hove Albion. After Brighton had Florin Andone sent off in the 30th minute, Southampton eventually made their numerical advantage count with two second half goals from Moussa Djenepo and Nathan Redmond.
