Chelsea manager Antonio Conte has explained why he splurged close to £60million on transfer deadline day.
Luiz’s return from Paris captured the imagination of supporters but Conte has hinted that Alonso’s move was perhaps the more crucial of the two transfers.
Branislav Ivanovic’s position has come under increasing scrutiny and reports suggest Cesar Azpilicueta could move back to his original spot to accommodate Alonso in the side.
Fellow right-back Ola Aina is also waiting in the wings to leave Conte grateful to have a left-footed player in the mix for the long campaign.
"We reached two targets, two good signings for us,” Conte told Chelsea TV.
"I think they can improve our squad and now it is right to work with David Luiz and Marcus Alonso to put them in our idea of football.
"It was important to bring in Alonso because he is left-footed - in the squad we have three [full-backs] who are right-footed.
"He's played in England before and for this reason he has good experience of this League.
"The same goes for Luiz. He played with Chelsea , is a good player and can bring a good personality.
"Now we have to work on the defensive situation, on the defensive line.
"We have to work to improve our physical condition, our tactical condition and to try to continue our good season."
Chelsea return to action after the international break with a trip to Swansea City on Sunday afternoon.