The McLaren was four-tenths faster through Rivazza. The Aston Martin was close everywhere else.
Piastri qualified first. Alonso qualified fifth. The gap between them was 0.761 seconds.
Half of that came from three corners.
Key Finding
Piastri took four positions off Alonso in Sector 3 alone. The other two sectors were dead even.
Where did Piastri find half a second?
ALO vs PIA — sector-by-sector breakdown
The red bar on the right is Sector 3 — Variante Alta and the Rivazza complex. That's where the McLaren pulled clear.
▲ ALO faster▼ PIA faster
S1: -0.193s · S2: -0.194s · S3: -0.374s
Key Finding
Piastri took four positions off Alonso in Sector 3 alone. The other two sectors were dead even.
The first two sectors were a wash. Piastri gained two-tenths in Sector 1 and two-tenths in Sector 2. Close racing. Normal margins.
Then they reached the high-speed section at the back of the circuit. Piastri was 0.374 seconds faster through Sector 3. That's four-tenths in six corners. The Aston Martin wasn't slow. The McLaren was somewhere else entirely.
What does four-tenths in Sector 3 look like?
ALO (Lap 18) vs PIA (Lap 17) — fastest laps compared
Watch the blue line climb away in the final third of the lap — that's the McLaren carrying more speed through the fast left-handers.
ALO (Lap 18)PIA (Lap 17)
Fastest laps: ALO Lap 18, PIA Lap 17.
Key Finding
Piastri took four positions off Alonso in Sector 3 alone. The other two sectors were dead even.
This isn't a tyre story or a strategy story. Both drivers were on soft tyres for their fastest laps. Alonso's came on Lap 18, Piastri's on Lap 17. The track was stable. The conditions were identical.
The McLaren simply had more rear stability through the high-speed corners. Alonso couldn't match it. He didn't need to lose time anywhere else — the Rivazza complex cost him four positions on its own.
Key Finding
Piastri took four positions off Alonso in Sector 3 alone. The other two sectors were dead even.
Monaco is next. No high-speed corners. No Sector 3 advantage to lean on.
Piastri will need to find his time somewhere else.