Obi suffered a knee injury in a high-profile English Premier League match against Arsenal in December and has been out since then. "I am gradually returning to fitness much earlier than expected. I was even hoping to be fully fit for this week's game versus Bolton, but I do not want to rush my return," said the Nigeria international. "It's a good boost for me and Chelsea because no team could be the same in the absence of several key players. Hopefully, most of us are coming back soon." The 23-year-old midfielder is expected to be fit in time for next month's friendly between Nigeria's Super Eagles and Guatemala in the USA. Mikel also said his London club have not given up on successfully defending their EPL crown despite being 10 points adrift of leaders Manchester United. "We have won our last two games and we need to sustain this run," he said. "We're getting our confidence back and I believe if we continue that way and the likes of Manchester United, City and Arsenal slip, we will be back at the top. It will be a great battle, but I am optimistic that it's not over yet."