Emery is excited to reunite with Luiz at Arsenal
Arsenal ended the summer transfer window with a double swoop as they added Celtic's Kieran Tierney and Chelsea's David Luiz to their ranks.
Following lengthy discussions with the Scottish champions, which dragged on for much of the summer, Arsenal finally settled upon a £25m deal for Tierney while Luiz is understood to have cost £8m after pushing for a late exit from Stamford Bridge.
Despite bolstering their frontline options through the signing of Nicolas Pepe, there were fears the Gunners would be left vulnerable at the back following the departure of captain Laurent Koscielny to Bordeaux.
But, having left it to the final day of the window, Arsenal now head into the new season with a combination of defensive youth and experience to hand.
Luiz joins after an apparent breakdown in relations with Frank Lampard. It's believed the Brazilian had fallen behind Andreas Christiansen and Kurt Zouma in the club's pecking order.
The 32-year-old, who first moved to Stamford Bridge in 2011 before later returning in 2016 after a two-year spell at Paris Saint-Germain, trained separately from his Chelsea team-mates on Wednesday in an attempt to force through the switch to Arsenal.
Unai Emery, who worked with Luiz at PSG, said his experience can help strengthen Arsenal's troublesome defence.
"David has huge experience and I look forward to working with him again," he said. "He is a well known player and adds to our defensive strength."
Tierney and Luiz follow Daniel Ceballos, on loan from Real Madrid, William Saliba and Pepe, the latter costing a club-record £72m.