THE AFL's decision to trial restrictions on teams making interchanges has put a severe dent in Sydney's hopes of finally winning a pre-season cup match.

Swans coach Paul Roos made it clear yesterday that Sydney now would be forced to play a weakened team against Hawthorn on February 17 in Tasmania.

Sydney has yet to win an opening-round match of the pre-season competition since Roos took over as coach in 2002.

Having exited the finals early last year and having three extra weeks to prepare for the coming season as a result, Roos indicated recently that several star players would be likely to play in the NAB Cup match.

But the AFL announced this week that while the number of interchange players for each team will be increased (from six to eight), each club can have only 16 interchanges a quarter, a total of 64 a game in the cup.

The AFL's reasoning is that with interchange numbers rising significantly, there is a concern over the possibility of more injuries.

"We spoke to them as a group and put in submissions as a club and the coaches association meeting with them was quite good," Roos said.

"They admitted they didn't really have enough evidence and there wasn't anything to suggest injuries were going up, so we thought that's good, they're not going to do anything.

"So it came as a little bit of a surprise when they announced this change was going to be trialled in the NAB Cup. Based on our previous discussions, they said they were going to put it on hold for 12 months.

"And in a sense what they're saying is you can have two extra, but you're not going to be able to use them."

While he is likely to have many more of his senior players ready to play in Tasmania, not all would be ready to play much of the game, so Roos was hoping that with unlimited interchange he would be able to easily restrict the minutes of those who needed such a process.

"We made 84 interchanges last year in our NAB Cup game, so it's a significant difference," Roos said. "We've got to find five less changes a quarter, and at a time where you're players aren't ready to play.

"There are repercussions for your selections, no question, and I would suspect a few of those (senior) blokes now definitely won't play."