Web services have become important building blocks of distributed applications and have matured to the point where service lifecycle issues such as version management are now paramount. However, there is a lack of versioning support in relevant standards and tools. We present an approach which leverages the existing WSDL service definition model to build a versioned service hosting solution. We distinguish between a web service interface (published) version and its implementation version (private). We introduce the concept of a service interface proxy. This proxy, which can be generated automatically, implicitly defines the service interface version, and is published as the logical service endpoint. Client requests are routed dynamically by the proxy to appropriate implementation versions. We have implemented a prototype of our approach to demonstrate its applicability.