The Brazilian is due to return to the German club following a successful loan spell with Atletico Madrid, which culminated in Europa League triumph. But after Los Colchoneros decided not to purchase the player permanently, his future is now uncertain.
Bild claims that Diego's representative has travelled to Russia to negotiate a €10 million transfer, with Lokomotiv offering the player a three-year contract worth €9.5m per year.
The Russian side recently appointed Slaven Bilic as their new coach and have also completed a deal to bring former Tottenham Hotspur defender Vedran Corluka to the club.
However, they will face competition for the former Juventus player from Flamengo, who have already had two bids for the 27-year-old rejected, according to Terra.
Wolfsburg could be tempted to cash in on the playmaker, who currently earns €9m per season at the Bundesliga outfit.