Sussex 263 and 120 lead Australia A 373 (Burns 133, Harris 109) by 10 runs
Joe Burns provided Australia's selectors with a conundrum after matching Marcus Harris with a century for Australia A before the bowlers ripped through Sussex to put the tourists on the brink of victory on day three at Arundel.
Burns was a late inclusion in the Australia A squad, after suffering from chronic fatigue syndrome, and the team for this match after Matthew Wade was called up to Australia's World Cup squad.
Burns and Harris added just 11 to the 203-run opening stand they produced on day two before Harris fell caught behind for 109 but Burns kicked on to reach his century. Kurtis Patterson fell cheaply before Burns and Travis Head shared a 61-run stand until Head was given out lbw sweeping Luke Wells for 34.
Burns was eventually dismissed by a beauty from Mir Hamza, edging him to slip for 133 from 241 balls.
"My goal coming into the game was just to try and face as many balls as possible, so I'm satisfied with the performance," Burns said.
He added he benefitted from a more relaxed approach to his preparation following his time out with post viral fatigue issues.
"I've probably listened to my body a lot more," Burns said. "During the summer I was really pushing hard all the time trying to prepare as best as you can and every time I felt fatigued I just thought I had to work harder and do more. I probably just have a better understanding of where my body is at. I'm listening to it a little bit more now.
"Coming into the game, I was just trying to focus on being as fresh as possible. It's actually quite relaxing mentally coming into the game, again getting called in at the last minute probably helped with that and it just makes you relax when you get out into the middle."
Burns and Harris appear to be in a battle to partner David Warner in the opening Ashes Test but Burns said they were not worried about that against Sussex.
"As openers you're always working as a partnership, trying to get through the partnership and helping each other out in the middle," Burns said. "[Harris] has had a tremendous season and done extremely well and made plenty of runs. You saw in this game he walks out there, whacks them from ball one.
"There's a lot of players making a lot of runs. It's great signs for Australian cricket and honestly, as players, you just get out there in the middle and work with your partner to try and overcome the opposition. You don't really look at each other competing for spots. I've always thought that if everyone's making runs, there's a spot for everyone."
Usman Khawaja's hamstring injury may provide another spot in the Australia Test top order although Steve Smith is also set to return. Burns said he was bitterly disappointed to see his Queensland team-mate get injured, but would bat anywhere if required.
"I was shattered for him," Burns said. "Hopefully it's not too bad. It's a cruel game sometimes. I feel comfortable anywhere. I've batted in a lot of different positions in the order in the past. Hopefully Uzzie [Khawaja] is there though. He's made that No.3 spot his own and is a really integral part of the Test team. As a team-mate you don't really want to think like that, you just hope he can get back playing and recover as quickly as possible."
Australia A collapsed against the second new ball following Burns' dismissal falling from 313 for 3 to 373 all out, but their bowlers tore through Sussex's batting line-up in the afternoon.
Bird got the ball to swing and nip as he claimed three top-order scalps in two overs before Holland found some purchase to give Patterson two catches at slip. Pattinson blasted out the tail with pace to leave Australia A with just 11 runs to win on the final day.