An 800m runner who probably has sub 45.0 potential for the 400, incredible.
Based upon the perceived relaxation he maintained in Rieti while re-breaking his WR he definitely has my confidence in him going sub 140.
In Berlin the rabbit cut 48.65 for the first 400. That translates to 8.22m/s. Rudisha looked to be 2 - 3m behind so let’s say he went 48.89-49.01. Going 141.09 for the 800 gives him 52.08 - 52.2 for the 2nd 400
139.98 translates to 49.9 splits
I say he does it
If I’m his coach I aim for increasing his speed to 45 low or even sub 45 for the 400 and his speed reserve will cover the spread