Roger Johnson has warned Cardiff City's "under-performing" stars will face the axe should the Bluebirds not improve.

Cardiff beat Southampton in their Championship opener but Johnson says City's squad is now big enough for boss Dave Jones to be ruthless.

"We under-performed," goal hero Johnson admitted. "All of us are now battling for a place in the team so no-one can just expect to wear the shirt.

"We've a much larger squad and the boss can now change things if he sees fit."

The FA Cup finalists needed a 90th minute winner from defender Johnson to beat a Southampton side that only escaped relegation to League One on the final day of last season.

Jones not only kept the majority of his Wembley heroes over the summer but the Bluebirds boss has strengthened his squad with half-a-dozen new boys.

Teenager Aaron Ramsey's £5m move to Premier League giants Arsenal and the release of aging attackers Jimmy Floyd Hasselbaink and Robbie Fowler were the only departures from Ninian Park during the close season.

606: DEBATE I felt we were a bit lacklustre and Southampton seemed quicker to the ball at times cathaysblue

"I have the ability to change things now," Jones told BBC Sport.

"I was able to throw quality and pacy forwards like Paul Parry and Jay Bothroyd on against Southampton late on, which I couldn't do before.

"Players like that can change games while Ross McCormack, who was already leading the line with Steve Thompson, is also quick.

"I had four forwards on at the end which highlights the depth of this squad - and that is very important for a manager as you need to have a few tricks up your sleeve.

"And hopefully I can get one or two more players in to add to the competition for places.

"I will wait until the end of the August transfer window if I have to or I might bring in another player on loan. But competition for places is so vitally crucial if you want success."

Steve Thompson epitomises Jones' argument as the transfer-listed Scottish striker showed against Southampton that he can be a goal threat as he fired home Cardiff's opener.

The 29-year-old has been criticised for his lack of goals but Johnson says the man they call 'Thommo' has revelled in the scrap with Parry, Bothroyd and McCormack for one of the two striking berths.

"Thommo has done well pre-season," acknowledged centre-back Johnson after City's Saints win.

"He deserved his start and after his goal, the lads were delighted for him. And when a striker scores, it is hard to take them out of the team."

"We had a good bench today, players that can change a game and that's what happened.

"A draw was a fair result, Southampton could feel very hard done by because we didn't play well.

"I am disappointed not to keep a clean sheet but the most important thing is taking three points."

Jones told his Cardiff players that they "did not perform to their capabilities."

And issuing a shot across their bows, Jones warned: "I've got options to change things now if I feel things are not working."