John Obi Mikel has selected a combined XI ahead of Chelsea’s match against Arsenal this weekend, which included an interesting decision between Kai Havertz or Nicolas Jackson for the striker position. Chelsea host Arsenal on Sunday in a Premier League fixture, but which centre-forward will come out on top? For the Blues, Nicolas Jackson, 23, has been enjoying a superb individual campaign as the main man to lead the line. Chelsea great Gianfranco Zola has even said Jackson is really improving this season. Meanwhile, Arsenal’s main central striker is former Blues star Kai Havertz. The 25-year-ol…