Capello named Denisov, demoted to Zenit's reserve team last month after he refused to play for the club and issued an ultimatum to renegotiate his contract, in his 24-man squad on Tuesday for the games against Portugal and Azerbaijan.
Striker Alexander Kerzhakov, dropped by Zenit for "improper behaviour" last month before being recalled after making peace with the club's coach Luciano Spalletti, was also included.
However, there was no place for former national team skipper Andrei Arshavin because the Arsenal forward has seen little action for his London club this season.
Former England manager Capello, who replaced Dick Advocaat following Russia's poor showing at Euro 2012, also dropped experienced strikers Roman Pavlyuchenko and Pavel Pogrebnyak.
Former Chelsea winger Yuri Zhirkov, who joined wealthy Anzhi Makhachkala last year, was also left out, making way for two newcomers from Lokomotiv Moscow, Dmitry Tarasov and Maxim Grigoryev.
The Russians have made a flying start in their World Cup qualifying campaign under Capello, winning both matches.
They face Group F rivals Portugal in Moscow next Friday before hosting fifth-placed Azerbaijan four days later.
Goalkeepers: Igor Akinfeyev (CSKA Moscow), Anton Shunin (Dynamo Moscow), Vladimir Gabulov (Anzhi Makhachkala)
Defenders: Alexander Anyukov (Zenit St Petersburg), Renat Yanbayev (Zenit St Petersburg), Alexei Berezutsky (CSKA Moscow), Vasily Berezutsky (CSKA Moscow), Sergei Ignashevich (CSKA Moscow), Andrei Yeshchenko (Lokomotiv Moscow), Vladimir Granat (Dynamo Moscow)
Midfielders: Igor Denisov (Zenit St Petersburg), Roman Shirokov (Zenit St Petersburg), Vladimir Bystrov (Zenit St Petersburg), Viktor Faizulin (Zenit St Petersburg), Alan Dzagoyev (CSKA Moscow), Denis Glushakov (Lokomotiv Moscow), Dmitry Tarasov (Lokomotiv Moscow), Alexander Samedov (Lokomotiv Moscow), Dmitry Kombarov (Spartak Moscow), Diniyar Bilyaletdinov (Spartak Moscow)
Forwards: Alexander Kerzhakov (Zenit St Petersburg), Artem Dzyuba (Spartak Moscow), Alexander Kokorin (Dynamo Moscow), Maxim Grigoryev (Lokomotiv Moscow).