Melbourne, Feb 15 (IANS): The squeeze is on for places in Australia's one-day side and Mitchell Marsh is in no doubt that Shane Watson remains a crucial part of the co-hosts' quest for a fifth ICC World Cup title.

Australia's selectors will have plenty to ponder about in the coming weeks as they attempt to fit captain Michael Clarke and star all-rounder James Faulkner into the starting eleven for a team that affirmed their status as tournament favourites with a 111-run victory over England in their Cup opener Saturday.

"I still think Shane's the premier all-rounder in our team and he's such a vital cog for us going forward in this World Cup," Marsh said.

Clarke will regain the captain's armband and a place in the middle-order when he returns from injury against Bangladesh Saturday, while Faulkner is making good progress from a side strain and is expected to be declared fit at some point in the group stage.

Both would be considered automatic selections in Australia's best XI, but just who they'll replace in the side will create no shortage of deliberation among the national selection panel.

Stand-in captain George Bailey all but conceded Friday that he will be left out when Clarke returns, but the Tasmanian sent a reminder of his quality with a crucial half-century against England.

Bailey has also led the side to two ODI series wins during the Australian season, against South Africa in November and in the recent tri-series against India and England.

And Marsh, one of the players most likely to make way for Faulkner, muddied the waters further with a five-wicket haul at the MCG to go with his powerful knock of 23 from 20 balls as Australia chased quick runs late in the innings.

The strong performances from Bailey and Marsh have put the focus on senior all-rounder Watson, who edged a Stuart Broad outswinger first ball.

Watson has scored one half-century from eight ODI innings this season, a match-winning 82 against South Africa at the SCG, and has one wicket from eight matches at an average of 200.

But Marsh said there is no question among the playing group of Watson's position in the side.

"All of us know how important he (Watson) is for us. To be fair I think most blokes (would have) nicked that ball (from Broad). It was a cracker."

"It's the one ball you don't want when you go in there first ball. It's obviously going to be a tough selection for the selectors this week but I think it's a good one.

"All the batters are in form which is great for us. This best thing about this squad is that we've got 15 blokes who don't really care what the XI is, we just want to win and build momentum.

"We're all fighting for spots but at the same time we all want to win."