Both Piastri and Lando Norris showed well in the opening two sessions, Norris fastest in Free Practice 1.
Though his Aussie counterpart was 10th it was a promising start with the position in the session not a true reflection of the pecking order.
Ahead of Piastri were Yuki Tsunoda and Lance Stroll, two cars that are expected to fall behind McLaren come qualifying.
He was also only 0.3s off the outright pace, a gap which expanded to 0.8s in Free Practice 2, when Charles Leclerc went fastest.
“We seemed very strong at some points, not as strong at other points,” Piastri opined.
“It’s going to be interesting to see where we come out. But I think there’s some definite positive signs.
“Just got to try and get it all together, which I think everybody’s struggling with a little bit with the wind.
“But yeah, good fun to be back at home.”
With overtaking difficult in Albert Park, qualifying has increased importance when it comes to determining the probable outcome of Sunday’s race.
As a result, that is where McLaren will focus its efforts in Free Practice 3.
“It looked very tight, as always, this year,” Piastri set of the field spread over a single lap.
“If we’re a little bit quicker we’ll be right at the front. If we’re sort of how we were in FP2 there over one lap, we’ll be towards the back end of the top 10.
“That’s kind of where we’ve been, the last two rounds, so hopefully we can make the car a little bit more consistent.
“But when it’s been good, it’s been very good.”