As pleasant as Australia's seaside diversion was after the gloom of the Lord's Test, the three-day match in Hove provided few clear answers to their many selection questions. Guessing at the XI who will take the field at Old Trafford later this week requires a Kiplingesque amount of "ifs" and just as many "buts". Definitive? The only definitive observation to come out of the past few days has been that the team's catching has been dreadful.

It is not that nobody performed with bat or ball - Steven Smith scored an unbeaten hundred, Ed Cowan and Phillip Hughes both made fifties, Jackson Bird challenged the Sussex batsmen - but that none of it means very much. How much stock could the Australians really take from a three-day friendly against a weakened county side on a bouncy surface that won't resemble that at Old Trafford, with a laughably short boundary on one side?

That the squad has been split across cities - and even continents, for David Warner has been in Africa - has not helped clarify matters. The team management decided that the openers, Shane Watson and Chris Rogers, would gain more from working in the nets at Lord's under the guidance of batting coach Michael di Venuto and fielding coach Steve Rixon than they would from playing Sussex. Peter Siddle was with them.

Warner will rejoin the squad in Manchester on Monday, having just mauled South Africa A for 193 in Pretoria. How do the selectors gauge his performance? It was on a small ground in a game where Glenn Maxwell also thumped a quick 155 not out and South Africa's Dean Elgar made a career-best 268. On the other hand, Warner was facing Kyle Abbott and Marchant de Lange, two wonderful young fast bowlers who have already thrived in Test cricket.

If Warner plays, where does he bat? And who misses out? Rogers and Watson seem certain to remain at the top of the order, which would mean one of Usman Khawaja, Hughes or Smith would have to make way for Warner. Smith scored an unbeaten 102 against Sussex, but is that enough to make him safe? Khawaja showed encouraging signs at No.3 at Lord's, but did little in the tour match.

Hughes tallied 122 across both innings in Hove and is Australia's leading run scorer on the tour, with 436 at 62.28. He made an invaluable 81 not out in the first innings at Trent Bridge, but since then has had three Test failures. Perhaps most importantly, he struggled against Graeme Swann's spin, and if the conditions at Old Trafford are as dry as expected and England include two spinners, he might be the man to miss out.

But what would such conditions mean for the attack? One spot is vacant due to James Pattinson's series-ending injury, but will it naturally go to a fast bowler? Or would the selectors consider using Nathan Lyon and Ashton Agar as a dual spin attack? Neither man had much impact against Sussex and while it is true that the conditions were better for the fast men, Monty Panesar managed to claim three wickets.

Lyon struggled in his first spell and seemed low on confidence, but he did improve as the match wore on. He found some dip and drop, and tempted the batsmen at times. His one wicket could have been two, had Agar held on to a skied chance from Taylor. Agar, meanwhile bowled better early and picked up a few edges, but was outbowled by Lyon as the match progressed. His lack of wickets in the first two Tests cannot be ignored.

Including two spinners might be risky, but can Australia really afford to keep overlooking Lyon, who has claimed 76 wickets in his 22 Tests? There must be a temptation to push for Bird, given the way he swung the ball against Sussex and hit naggingly accurate lines. But how relevant will his form be if they arrive in Manchester to see a dusty surface and a fine weather forecast?

They cannot forget The Oval Test of 2009, when Nathan Hauritz was overlooked on a dry pitch and Stuart Clark struggled in conditions that did not suit him. There is more than a little bit of Clark in Bird, and likely more than a little bit of The Oval surface in the Old Trafford wicket the teams will encounter. Bird might have edged Starc out of contention, but who could really say for certain?

The only thing that is certain is that some remedial fielding drills are in order after the Australians put down roughly half a dozen chances against Sussex. And if they do that against England in Manchester, it won't much matter who the selectors have picked.

Brydon Coverdale is an assistant editor at ESPNcricinfo. He tweets here