''I am very much there and it's a big role. After two years, or whenever he quits the game, obviously I have to take a step forward, take on the responsibility,'' Harbhajan told a sport's website.
''Obviously it's a very very big task, but I have done well in the past and I am sure if I keep working hard on my game...it's up to me how well I want to take this job and what I want to do,'' he added.
Harabhajan said despite his career being on the downside off late, he was happy with what he had acheived so far. The off-spinner said he wanted to be in Kumble's position before retiring.
''I have already got 240-odd wickets in Test cricket, and at my age not many people have achieved that. I am still 26 and I have age on my side. If I am really keen, which I am, that I want to be someone like him and finish with 500 odd wickets. I would like to see myself where he is today,'' he said.
Harbhajan blamed injuries for the slump in his form and admitted that he could not fulfill the expectations he raised after taking 32 wickets in the 2001 Test series against Australia at home.
''I got injured and it took me seven months or so to get back into the team. Things had changed - we won. We did well in Australia, Anil took lot of wickets. We did well in Pakistan. After that I came back, played my first game against Australia and I took 11 wickets in Bangalore, we lost that game. I was happy to make a comeback but we lost that series."
''Expectations had changed, people wanted me to take 32 wickets and that cannot happen,'' he explained.
Harbhajan said during his lean phase he turned to Kumble for advice and conceded that despite the competition for a place in the side, he gained by having the veteran bowler around as it helped him get over the tough times.
''Whenever I am not bowling well, I go back to my basics. I know what I have to do and I keep talking to my seniors - Anil and the great batsmen in my team. They have played all over the world and played the best spinners. Having Anil around is a big bonus and when you bowl together you do pick up a lot of things from the bowling partner,'' he said.
The off-spinner rejected suggestions that he was a better ODI bowler compared to Tests and said apart from the home series against England last year, when he failed to get many wickets, he had bowled well in both forms of the game.
''I played three Tests against England in India. And it was the worst period for me, I was bowling well but I didn't get wickets.
Nothing was going in my favour but you cannot complain about dropped catches and all that. I did not get many wickets in that series and it stays at that. Apart from that, things have gone really well and I am very happy with whatever I have achieved,'' he said.