If you ask a central midfielder like Senna to chase Arshavin down it's dangerous because it leaves gaps for others to exploit and Russia have plenty of other options.
Senna will take care of Arshavin when he goes into his area in front of the Spain back four, but otherwise the other Spanish defenders will have to deal with him.
Arshavin is so good he plays passes other people wouldn't have thought of and most people can't see. He's phenomenal.
"~RS~q~RS~~RS~z~RS~25~RS~)