Prior to the players travelling out to Asia, Tomas Kalas was one of three who had been away on loan last season that Jose Mourinho confirmed would be part of his squad for the campaign ahead.
The others were Romelu Lukaku and Kevin De Bruyne and the manager started all three in the opening pre-season game on Wednesday in Thailand.
Kalas and Lukaku, like most of the initial line-up, were withdrawn at half-time while De Bruyne played on longer, but for the Czech defender his 45 minutes are a sign of exciting times.
Signed by Chelsea in January 2011, Kalas began his two-year loan at Vitesse Arnhem in the summer that followed and was then an Under-19 international who had played a handful of first team games in the Czech league and similar amounts for Chelsea's youth and reserve teams.
'I think I have more quality on the ball now,' he tells the official Chelsea website as he considers his development since.
'The Eredivisie (the Dutch top flight) is known for football quality and there I learnt a lot, especially in the second year when I was playing right-back because in that position you need more technical skills, but both years were quite successful, I was playing all the games and as player of my age that was the most important thing.'
Prior to last season Kalas had always been a central defender and the very first time he tried his hand at right-back was in the early weeks of 2012/13, against Feyenoord at home.
'I didn't expect it but the coach came to me and said you have some skills to play on the right of defence,' he recalls. 'It was more difficult because we were playing against a really good team but we won 1-0 so nobody could say anything.'
There he remained for the rest of the season as Vitesse finished fourth.
In September Kalas made his debut for the senior Czech international side, coming on for the closing minutes of a friendly, again at right-back. In February he won his nation's award for the best young player of the year, sharing a stage with Petr Cech who was fulfilling his annual booking to collect the Czech Footballer of the Year honour.
'That is quite a good story,' smiles Kalas. 'I have a father not in age but a father in experience, and I am sure Petr is going to help in my development.
'Being part of the squad at Chelsea is what I was hoping for when I signed for the club. I didn't know that it would come so early, and that is why I went on loan to Vitesse to improve myself.
'I didn't expect that after two years I would be part of the first team squad but especially now it is exciting because how many players from my country at 20 years old can say they have played 63 games in the Eredivisie, and they can be part of the main squad at Chelsea?'
Marco van Ginkel is another who is joining up with Mourinho and our players for the first time having honed his talents in Holland at Vitesse, and Kalas is well-placed to brief about the summer purchase who is just a few months older.
'Marco is one of the biggest talents of Holland and one the best central midfielders of his age in Europe, and I think he deserved his move to Chelsea.
'The last two years he was playing so well and without him and without Wilfried Bony we couldn't have reached the Europa League both seasons. So Marco was one of most important players in our squad so for me it is not a surprise he is here.
'His distribution is good but he is also unbelievably strong for his age and he can make runs as a No. 10 or as a No. 6 behind the strikers. He scored 11 goals last season and for a No. 6 that is really good, so he can play offensively as well.'
It was by his defensive play that Kalas was judged on Wednesday against the Singha All-Stars, and alongside John Terry in central defence he equipped himself well. Training is equally important at this stage of pre-season and the young defender is pleased with both this week's game and the sessions either side of it.
'In Bangkok the other team were playing counter-attack football and we didn't lose much of the ball in the first 45 minutes so they didn't make many chances to score, so for us as centre-backs I think more difficult games will come.
'Every day training with Jose Mourinho is like a high school for me,' he adds enthusiastically. 'I am enjoying learning in every training session and trying to develop myself, and if we train hard and it is difficult then in the games it can be easier.'