Mensik’s indoor serve gives this match a route to quick holds: he won 25 of 28 first-serve points in each of his last two hard-court outings. His Vienna opener took 63 minutes and produced just 16 games. Serve-led control is the clearest reason to expect a compact total.

Mannarino, 38, has played two qualifying matches and a two-and-a-half-hour opener against Buse in a compressed stretch. His serve was broken repeatedly there, and he won only 45% of second-serve points; that is precisely where Mensik’s return can apply pressure. At 2.028, the under 21.5 is worth taking.

The likely score patterns sit around 19 to 21 games, such as 6-4, 6-3. Mannarino’s comeback from 0-6 against Buse is a reminder that he can recover and disrupt a match; a long set or tie-break is the main danger to the lean.