Those results have taken away some of the buzz surrounding the squad following their opening-day smashing of the Blues.
But Robson believes that a win over Leicester City, who are off to a fine start and currently sit third in the Premier League table, can spark the side back into a challenge for place in the top four.
"We have got to step it up against Leicester and put on a really good performance and get good results that will get everyone buzzing again,” he told MUTV.
“Yeah, they’ve had a good start to the season and have good young players. That’s why it’s important we have a good result against them.
“I think they will up there challenging for the top six and they will want to get back into Europe. It’s a tough game as they have some good players but that’s the challenge for us.
“If we want to be in the top four, we need to be beating teams like Leicester at home.”
The match against Leicester kicks off a four-game run in the Premier League that also will see United face Newcastle, West Ham and Arsenal before a showdown with league leaders Liverpool on October 20.
And Robson thinks a good run of form over that short span would be enough to get the season back on track, if the Old Trafford side can put their loss to Palace behind them.
“The boys have just got to get the Crystal Palace game out of their system, you know. We didn’t perform brilliantly on the day and we could have done better,” he said.
“Maybe if we’d scored the penalty (by Rashford against Palace), but we got beat and that’s in the past. Ole thinks we are improving all the time, which I agree with, as I think we’ve played pretty well in the games I’ve seen.
“The atmosphere around the place is really good. All we’ve got to do is put a good set of results together, over a short period of time, so let’s get the season firing."