Zinedine Zidane is rumoured to have completed his first signing since returning as Real Madrid manager with the capture of Frankfurt striker Luka Jovic. According to Spanish publication Diario AS the Serbian international will join Los Blancos for a fee of £51m, but fringe player Mariano Diaz will move to the German club as a sweetener in the deal. It is thought Frankfurt will receive £40.8m while Benfica, who still own a percentage of the player’s rights, will earn £10.2m. Jovic has been in superb form in the Bundesliga this season, netting 26 times in 44 games for Frankfurt. Zidane has already talked of his wishes to rebuild a squad who have suffered a poor season, and the 21-year-old Jovic is likely to be the first of a number of new faces. He is expected to support Karim Benzema next season, and may be seen as a long-term heir to the French striker, who is 31 years old. It remains to be seen whether he can live up to expectations at the Bernabeu, but Zidane is clearly a big fan of the youngster, who has won four caps for his country. Diaz, who famously took the number seven shirt that…