Ends in 01 (regular!)
Reverse mode — you defend.
Is L = { w ∈ {0,1}* : w ends in 01 } regular?
You · move 1
You are defending L = { w ∈ {0,1}* : w ends in 01 }. Claim a pumping length n — the engine will then choose a string and try to break your decomposition of it.