Brendan Rodgers has warned rivals his Celtic team are fitter than ever as they shape up for the new season.

Celtic returned to pre-season training on Monday and manager Rodgers has been delighted with the state of his squad.

After racking up a gruelling 61-game campaign last term, the Northern Irishman has been delighted to see the bulk of his players get a month off following their 'double treble' triumph.

Now refreshed and rejuvenated, Rodgers says his team are looking in tip-top shape as they prepare to return to action, with Champions League qualifiers approaching.

Celtic fly to Austria on Monday for a 10-day training camp, and Rodgers told Celtic TV: "It was important that a lot of the players got a good rest. Not all of them are back as there are some still away on international duty.

"The players had nearly four weeks which is very important. When you play the number of games that we play it's absolutely critical you come out the battle and have the rest.

"The players have done that, come back and this is the fittest they've come back.

"This is my third pre-season now and, in terms of where they're at, they've come back very fit. In these opening few days they've shown a great level of fitness and that helps."

Rodgers' men will also squeeze in three friendly clashes against local side SK Vorwarts and Czech sides Bohemians 1905 and Sparta Prague during their stay in the foothills of the Austrian Alps.

They then head to Dublin on July 7 for the final leg of preparations before opening their Champions League qualifying bid away to Armenian side Alashkert three days later.

And it is vital his men are up to speed by that point, says Rodgers.

"There's a beauty of the Champions League phase in that you know you're into the competitive games fairly quickly and this is now my third experience of that so that's good," he said.

"The opening period for the season is about qualification but in terms of our objectives, we're looking to develop our physical and football fitness. That's still key and the players have come back with a really good base which I'm very happy with.

"We'll be looking to develop that over the next few weeks so that when the games come we're at a really good level. The group look fit, they look strong and we've got players coming back. I would hope we'll be in a really good position with the squad."