England and Manchester United's all-time top scorer Rooney, 34, joined from Major League Soccer side DC United but is not eligible to play until January.

His first appearance in the dugout as coach was on 30 November as Derby drew 1-1 with Queens Park Rangers.

"I could play. I didn't have long off - if the game was tomorrow, I'd be ready," he said.

"It feels nice being back home and getting prepared for January.

"It's been good the last few weeks, training, getting to know the players and staff and getting ready for first game. I feel good physically."

But he admitted: "It's frustrating training and not being able to play."

Rooney, whose first game as a Derby player could be on Thursday, 2 January at home to Barnsley, first visited his new Rams team-mates in early November having left DC United in October.

Derby are currently 16th in the Championship under manager Phillip Cocu, nine points adrift of the play-off places.

On the challenge facing him in the Championship, Rooney added: "The difference here is it is a very tight league. We're not where we want to be but we're not too far off the play-off spots.

"This league is about being consistent. Without a doubt [the play-offs are still achievable]. I've lost the Premier League title with about four minutes to play, it's not even Christmas yet so there's a long way to go.

"In all three games I've been to, in parts of games there's been a lack of urgency, a lack of composure, and not enough chances created. It's something we're working on and trying to put right."

Management is 'what I want to do'

During his time with Manchester United, Rooney won the Premier League five times, as well as the Champions League, the FA Cup and three League Cups.

Having spent 13 seasons with Manchester United, he departed Old Trafford in July 2017 to return to childhood club Everton, but moved to America after just one season.

And, as he begins his first coaching role with Derby, Rooney believes his experiences will set him up well for a future managerial career.

"It was a great experience for me in the States. It's so different to the football over here and it will benefit me in the long run," he said.

"I don't know too much myself about me as a coach. The manager has been great with me, I'm training with players and then having an input with the manager and other coaches off the training pitch.

"In terms of going into meetings with staff, I've been involved and giving my opinion on different things."

On his desire to become a manager, Rooney said: "Yes, of course. I've been around this game a long time, it's what I want to do and opportunities like this one to play and also have a foot in the other side of things will only benefit me."

Although there remains uncertainty over where Rooney will play on the pitch, one aspect that has been confirmed is his controversial squad number.

He will wear the number 32 shirt at Derby, after the Rams secured "a record-breaking sponsorship" deal with shirt sponsor online casino 32Red "off the back of" the former England captain joining the club.

Sports Minister Nigel Adams warned Derby should consider the impact that move would have on those vulnerable to gambling, however Rooney said he has "no concerns at all".

Rooney added: "It is a squad number. It could be any number. I could have worn 8, 9, 10 but they weren't available."