Does staying in the Airport for 5 hours count as an entry?

Basically, I am going to Hong Kong from Siem Reap, but there'll be a connection flight in Shanghai, where I'll stay for 5 hours.. The thing is: after Hong Kong, I'll go to Guangzhou, and start travelling inside China for almost 1 month.. And I have only one entry (single entry visa).. If I take this flight, will it count as an entry, not allowing me to enter Guangzhou from Hong Kong?