Willis had never even played at Wimbledon before Monday’s shock win against world number 54 Ricardas Berankis.
Now he will be strolling out on to Centre Court in front of 15,000 people.
“He has to try to visualise himself walking out there so he doesn’t spend the first 25 minutes looking around,” said Henman.
“If he does that then he will be down a set and a break fairly quickly.”
Fellow BBC Sport commentator Andrew Castle added: “My advice would be smile, enjoy it and realise that whatever happens it will be over in a couple of hours. He has to just go for it.”
