A TCP intermediate device receives a SYN packet from a TCP client that is destined for a TCP origin server and indicates support for TCP fast open (TFO). A SYN-ACK packet is transmitted to the TCP client that includes a TFO cookie set by the TCP intermediate device. The TCP intermediate device receives a first ACK packet from the TCP client. A SYN packet is sent to the TCP origin server and a second SYN-ACK packet is received in response that does not indicate support for TFO. An ACK packet to the TCP origin server. Sometime after the TCP connection is completed, the TCP intermediate device receives a SYN packet from the TCP client that includes the TFO cookie and a payload of data. The TCP intermediate device establishes a TCP connection with the TCP origin server and transmits the payload of data to the TCP origin server.