After leaving McLaren for Ferrari, Sainz has often encountered his former team on track as the two outfits battle over third place in F1's 2021 constructors' championship, a fight which is currently swinging Mclaren's way by just 15 points.
Last weekend's British Grand Prix was the latest race in which Sainz was fighting a McLaren, having shadowed Ricciardo for large spells of the Silverstone race as they fought over fifth place.
As had happened in earlier races, Sainz was unable to beat a McLaren in a straight fight as the McLaren's excellent straightline performance, driven by its Mercedes engine, proved too much for Ferrari.
"Unfortunately, it has happened to me now a few times that stuck behind a McLaren I am not able to pass," Sainz said after finishing sixth in Ricciardo's wake.
"It's not news, they have a very strong straightline speed, very strong deployment and power on exit of corners and it is probably one of the most difficult cars to overtake."
Sainz was left frustrated after an early overcut on Ricciardo failed to work out due to a poor pitstop from Ferrari, which left the Spaniard in the pitbox for ten extra seconds while his front-left wheel was tightened.
That ultimately meant Sainz would be stuck behind the Australian until the end.
"Yeah, unfortunately we were a step behind Ricciardo the whole race," he added.
"First on the medium, then we actually managed to overcut him with a very strong pace during the cleaner laps but unfortunately after the slow pitstop I had to go behind him again.
"On the hard tyre it was even more difficult to overtake him, because it just felt like the hard tyre in the high speed could not take the load of the dirty air and I was understeering a lot more, and I couldn't keep up with him in the high speed.
"Even though I had DRS I wasn't close enough to him to try to get him."