John Obi Mikel has welcomed the arrival of Brazil international David Luiz at Chelsea, and has made a funny remark about the Blues number 19 Diego Costa. <br /><br />Luiz spent three and a half seasons at Stamford Bridge before he was sold to Paris Saint-Germain, where he spent two years.<br /><br />The 29-year-old South American has returned to Chelsea for a second stint, penning a three-year deal hours leading up to the close of the summer transfer window on Wednesday. <br /><br />&ldquo;Welcome home @DavidLuiz_4 ! Remember to be nice to Diego 😉 🔵 ⚪️ #Carefree #KTBFFH , &rdquo; Mikel posted on Twitter, and this has been retweeted 3,600 times as at the time of this report. <br /><br />Luiz was involved in a row with Costa during the Champions League clash between PSG and Chelsea in 2015, with television replays suggesting that he elbowed the Spaniard. <br /><br />Both Mikel and Luiz are in line to play their first competitive game for Chelsea in the 2016-2017 campaign when the London club face Swansea City in the Premier League on September 11.<br /><br />Ifeanyi Emmanuel <br /><br />Photo Credit : Twitter.com <br />