Australia's coach has hinted there is no guarantee of an all- rounder Shane Watson getting a Test berth even if he is fully fit.
Watson has come under fire after his team-mate Ed Cowan scored 68 in the Melbourne test
Another stellar performance from Cowan in the second Test against India will make it difficult to break the new opening batsmen partnership with Dave Warner.
"There's pressure developing in every position in the Australian cricket team and that's a great position to be in. For this Test we're trying to get 12 into 11 (with the return of Ryan Harris)," Fox Sports quoted Arthur, as saying.
"When Shane Watson gets back, we've got to get 13 into 11, and when we get Patrick Cummins back, hopefully in Perth, we've got to try to get 14 into 11.It's a really good position to be in. I couldn't be happier. There are no guarantees for anybody," he added.
Though Watson has claimed 14 wickets, he averaged just 24 with his bat in 2011.
His situation has been compounded because he is suffering hamstring and calf injuries, and Arthur has backed the current top six batsman to continue performing against India.
Australia's new pace trio - James Pattinson, Peter Siddle and Ben Hilfenhaus, who aided the Melbourne win, might endanger Watson's chances of inclusion in the squad.
"I believe that's the best top six we have in Australian cricket at the moment. Obviously when Shane Watson's fit he comes back into the equation. But right now, with Shane Watson injured, those are our best six batters and we need to give them every opportunity to come through," Arthur said.