MADRID: Europa League holders Sevilla have strengthened their midfield by signing Frenchman Steven Nzonzi from English Premier League side Stoke City, the La Liga club said on Thursday. Nzonzi, 26, whose father is of Congolese origin, has signed a four-year contract which includes a buyout clause of 30 million euros ($33.1 million), Sevilla said on their website (www.sevillafc.es). They did not disclose any financial details but Stoke said on their website (www.stokecityfc.com) the deal was worth seven million pounds ($10.8 million). Sevilla's second consecutive Europa League triumph last season has earned them a place in the Champions League group stage for this term.