Tomas Berdych believes Novak Djokovic and Rafael Nadal have firmly re-established themselves as the world's top players.
Stanislas Wawrinka won the Australian Open title at the start of the year but current world No. 2 Nadal has since landed a record ninth French Open crown and world No. 1 Djokovic claimed Wimbledon glory earlier this summer.
Berdych feels Djokovic and Nadal, along with 17-time Grand Slam champion Roger Federer, have once again established themselves as the players to beat after difficult periods for all three players.
"There are three guys staying up there," he said.
"There was one change with Stan getting up there by winning the Slam at the beginning of the year. You really need to win a Slam to get there. Stan had a great run in Australia.
"Then Rafa and Novak. Nothing really changed after that. I wouldn't say it's really open there. It was just the moment Stan jumped up and took it. I think it's back to the old lines like it was before."
The 2014 US Open in fast approaching and Berdych is eager to win a Grand Slam himself, as well as breaking into the top four, but admits he needs to raise his game further in order to do so.
"If there's a recipe to do it, I would like to know it. We're all trying," he added.