Gustavo Kuerten's first tournament since September came to an abrupt end with a 6-2 6-0 defeat by Alberto Martin at the Valencia Open.
The former world number one had a surprisingly easy first-round win over fourth seed Olivier Rochus but was no match for Spaniard Martin.
Kuerten was sidelined for seven months following hip surgery.
"There are still a lot of things I have to do better to match a player like Beto (Martin)," said Kuerten.
"Today, he didn't give me a chance to run the match. He moved me well from one side of the court to the other."
The Brazilian, a three-times French Open champion, will continue his comeback at the Monte Carlo Masters.
In other matches on Thursday, in-form Spaniard Rafael Nadal comfortably saw off compatriot Guillermo Garcia-Lopez 6-1 6-4.
Fifth seed David Ferrer, a semi-finalist at last week's Miami Masters, defeated Irakli Labadze 6-3 6-4 and seventh seed Igor Andreev beat Italy's Potito Starace 7-5 6-1.