The Serbia international wasn't with the club during the Portuguese's first spell at Stamford Bridge, and reveals that his first impressions of Mourinho and his team have been good.
Ivanovic told the club's official website: "For us players, this trip is about hard work because we have to get our base fitness for the rest of the season and give our best in every session to help ourselves.
"The management and coaching has been impressive, and all the work has a high intensity and is very serious, which is what we need for the games.
"A lot of the work is based on fitness and physicality but it is all specific to football and it is very good."
Ivanovic made 59 appearances for the Blues in all competitions last season.