Salesforce could face competition from a surprising new place: Amazon.

According to new investment research from Jefferies, Salesforce partners picked Amazon as the 3rd biggest threat to Salesforce, trailing only Oracle and Microsoft. 

Amazon doesn't sell any customer relationship management products itself. But it has a bunch of partners who sell CRM solutions through its AWS Marketplace. Apparently, some customers are choosing these apps to piggyback along with AWS services such as data storage and compute power, rather than buying a CRM system separately.

The survey should be taken with a grain of salt — it only asked 85 Salesforce partners that mostly target medium-sized businesses. Salesforce and Microsoft play in this space, but most customers of the bigger CRM players like Oracle and SAP are large enterprises.

Still, it's another sign of how powerful AWS is becoming in the enterprise.