With Fabio Quartararo setting the noteworthy pace throughout the first practice sessions, FP4 showed that the Frenchman does have some serious competition in Catalunya. The first challenger to step into the ring was colleague Maverick Vinales, whose early pace on new rubber was not too shabby, in the low to mid 1:40s. The Spaniard led the session throughout and was one of the many riders favouring the soft rear tyre.
Pol Espargaro was tempted by the medium rear to begin with – like all KTMs – but then went on to show fine pace in the mid 1:40s on the soft. The younger Espargaro continues to enjoy his time on home soil to finish only two hundredths of a second down on Vinales and with Joan Mir another hundredth down, making it an all Spanish top three. Valentino Rossi breaks the spell in fourth, while apparently undecided between the medium and soft rear. Quartararo seemed to be haunted by some mysterious technical issues early on but his second machine worked just fine and allowed him to come within six hundredths of a second of Vinales, although fifth on the timesheets.
Brad Binder in sixth place was only two tenths off the lead, while Pecco Bagnaia, Franco Morbidelli, Johann Zarco and Andrea Dovizioso rounded out the top ten. The likes of Takaaki Nakagami, Cal Crutchlow and Alex Rins missed out on prime positions despite being only three tenths of a second slower than the leader.