For the second week in succession, Friday morning practice saw little activity as Jerez's tricky conditions were replicated in Portugal.
With the track never fully wet but too tricky for slicks until the closing minutes, for most of the morning the spectators just had a handful of CRT bikes to watch.
Spies was among the first of the big names to emerge, and by the end of the session 19 riders had been out to at least assess the conditions.
Nicky Hayden was quickest ahead of Valentino Rossi as the chequered flag fell, but Spies was still out on a quicker lap and came through with a 1m40.813s to deny Ducati a one-two.
Casey Stoner was fourth on the fastest Honda, followed by Gresini's Alvaro Bautista and the Tech 3 Yamahas.
Spies' championship leading team-mate Jorge Lorenzo was among those who chose to stay in the pits.