Jaap Stam attempted to dampen the high expectations of Reading supporters after a poor display saw his third-placed team lose 1-0 at home to QPR in the Sky Bet Championship.
Sections of fans - in a crowd of just 12,665, the lowest league gate of the season at the Madejski - booed at the end as Reading missed the chance to cut the six-point gap to second-placed Newcastle.
"It still looks good where we are but we need to be realistic," Stam said. "We are not yet to be able to say we want to win this league or we can easily end up in the first six.
"I've said this throughout the whole season. We're trying to work on something this season and eventually, hopefully, we will get to a certain level that you want to go to - the Premier League.
"You can't expect a team within six months to already be a contender for the Championship title or, compared to where they were in the past couple of seasons, in the top six."
Stam also paid tribute to QPR's performance as the Londoners received a welcome boost in their relegation fight with a third successive league victory.
"They played 5-3-2, defensively sitting and waiting, and that made it more difficult for us to create chances," Stam said.
"It was very tight, very narrow, and so credit to them for the way they defended.
"They waited for that moment to get out on the break and they succeeded in doing that. Well done.
"Sometimes, especially in the first half, we played the ball too quick and too long. It was disappointing tonight."
QPR won through a 28th-minute close-range effort from Jamie Mackie, the former Reading loanee who returned only last month after an eight-month lay-off due to an ankle problem.
Reading improved after half-time but rarely troubled QPR keeper Alex Smithies, apart from when a Yann Kermorgant header struck the crossbar.
"I've just told the lads how proud I am," QPR manager Ian Holloway said. "To stop Reading was a huge thing. Sometimes, you need to learn how to stop other people. I'm delighted for them.
"I want to work with people who want to be there and that's all you can ask for. And I thought you could see that in my team tonight.
"They'll all make mistakes but something has just clicked with us. It's a spirit, an environment."
In an apparent parting shot to midfielder Sandro and striker Sebastian Polter, who both recently left QPR, Holloway added: "If you find out some of your players aren't doing it or are lazy or don't do enough, then you've got massive problems.
"But my young lads see us now and that's what it's all about. The game is about wanting to be as good as you could ever be."