"I'm proud of them and I believe in them", he told BT Sport after the match.
"I trust Reece. He had an injury early season but he has got fit and has been training at a level where he deserved minutes and he did brilliantly".
James, who scored the equaliser in Chelsea's 4-4 draw with Ajax midweek, coped amazingly well with Palace star Wilfried Zaha, limiting the winger to only a handful of real opportunities.
"What better a test?"
Chelsea coach Frank Lampard named the youngest ever starting XI in Chelsea's Premier League history - with an average age of 24 years and 88 days - and the youngest of any team in the competition this season, and in the first half it was the hosts who went closest to scoring as a Willian free kick whistled past Vincente Guaita's post on 14 minutes. "It would be a tougher call if I was speaking to him when he was having a hard time and I was bringing a kid in but Azpi is playing really well for us. He's a great leader for the club and so important to us".
Now though, the Chelsea boss has come out to explain his decision of selecting Reece James over Azpiliceuta.
Chelsea also started James' fellow academy alumni Fikayo Tomori, 21, Mason Mount, 20, and goalscorer Abraham, 22, against the Eagles, as well as bringing Callum Hudson-Odoi, 19 and Billy Gilmour, 18, off the bench.
The west London giants registered a comfortable 2-0 win over the Eagles on Saturday afternoon and Willian had a key role to play for the opening strike from Tammy Abraham.
"Setting expectations was hard going into the season", he admitted.
"It might give me some selection problems going forwards but I want what's best for the team and it's a nice problem".
"But you never know with young players until you put them in, and when you put them in as a group even more so". "We've put in a lot of good performances, away from home and again today at home".