Chelsea defender Marcos Alonso attends training session at Chelsea's Cobham training facility on the eve of their UEFA Champions League round of 16 match against Barcelona. Pic/ AFP

Chelsea defender Marcos Alonso and midfielder Ross Barkley on Monday took part in a training session after having missed the past three matches, while David Luiz and Tiemoue Bakayoko were absent in the run-up to the Champions League game against Barcelona.