United face fifth-placed Chelsea at Stamford Bridge on Sunday before playing City and West Ham, currently in fourth, over the following two weekends.
"The three games are massive," said Solskjaer. "We've got Chelsea who are just behind us and we've got City away, who are in front of us.
"Of course, we can't let them run further away if we have ambitions of catching them, and we can't give Chelsea too much hope to catch us either.
"Every game is important and now until the international break will be a big period of six or seven games. We always say look at April and May to see how we are then. So, let's get to the international break and then we can focus on the run-in.
"I think it's going to be a long run-in. I don't think the positions will be decided early. This season it's unpredictable, we've seen teams going through bad phases then a run and who knows what's going to happen with injuries and how players react to circumstances.
"It's the shortest, long season ever with loads of games. For me, every game is massive and of course Chelsea we know how difficult that's going to be and how important that's going to be for us.
"It's still 38 games for every team. If you get a run good or bad it might impact you as a group and the culture.
"For us, bouncing back after a couple of setbacks we've had and going through now, it's an important period. Our mentality is really good and we look forward to these games."
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