Lukoil Racing's Gabriele Tarquini doubts he can maintain his sizeable margin over the rest of the World Touring Car field achieved in the series' first practice session at Algarve.
The 2009 world champion's SEAT was half a second clear of championship leader Yvan Muller in the session, and enjoyed a one second advantage over the third-placed RML Chevrolet of Alain Menu.
"This is the only circuit other than Estoril where we have tested this winter," said Tarquini. "We spent two days here, which was important.
"I did a good lap, but what is more important is how much Chevrolet wants to show this weekend."
Tarquini is the only non-RML Chevrolet driver to win a feature race this year, when he scored victory at the Slovakia Ring, but did not feature among the leaders in Austria.
"I was really suffering in Salzburgring with flu," said Tarquini. "For the races I was already recovering, but on Saturday it was a struggle. I am now back to 100 per cent."
SEAT Leons, Tdi-powered rather than the latest 1.6T-engined machines, took honours on the WTCC's last visit to Portimao in 2010. Local star Tiago Monteiro and Tarquini shared the spoils.
"I won here back in 2010, but things have moved on for us since then," said Tarquini. "At that time the Chevrolets were aspirated, not turbocharged, and we had the turbodiesel. I do like this circuit; it is early to say what we can achieve but I hope to be on the podium."