Carlos Sainz has said that he has been impressed with the progress being made by McLaren-Honda.
After a shocking 2015, the new Anglo-Japanese collaboration haa been making gradual progress this year and has arrived at Spa with a new Honda engine that will benefit from a full seven tokens of performance upgrades.
"They are almost the fourth car already and if their development works, they could be the surprise of the end of the season," Toro Rosso driver Sainz is quoted as saying by Marca.
"Great news for him and bad for us," added the Spaniard, referring to his countryman and friend Fernando Alonso.
McLaren is seventh in the constructors' championship but just three points behind Toro Rosso, and Sainz admitted that losing sixth would cost "important money for Toro Rosso".
