Charlton boss Athletic manager Johnnie Jackson has promised to “give it a right go” when Norwich City head to The Valley – but admits it’s hard to predict how strong a side his opposite number Dean Smith will name.

Jackson has taken the Addicks past non-league opponents Havant & Waterlooville and Gateshead – the first two rounds and now faces a side bottom of the Premier League and struggling to buy a point.

“It’s very difficult for me to predict,” said Jackson. “They find themselves in a tricky situation in the league and I know that will be Dean’s main focus. But at the same time he is not going to want a cup upset on his hands.

“I expect them to take the game seriously. They probably will make changes but he has the luxury of a putting a strong team out there whatever he does.”

Jackson will definitely be without central defender Akin Famewo as part of the loan agreement between the two clubs.

He also has concerns over striker Jayden Stockley, has 14 goals in all competitions this season.

Stockley missed Charlton’s 1-0 defeat at home to Wycombe Wanderers last weekend.

“It’s a bit of a tricky injury that he has got,” explained Jackson. “It is a bit of a nerve issue which is causing him a problem. It is a difficult one to get to the bottom of. It’s not quite right at the moment. It’s unlikely he’ll be involved this weekend.

“If there’s any doubt about him I have to protect him. We want to do well and win the game, but the league is the priority.”

Josh Davison looks set to come in should Stockley not make it.

Charlton have a big chance of a cup upset – one which might just erase a few painful memories for Jackson, who was their captain when they lost to Sheffield United in the 2014 quarter-finals.

“It was probably one of the biggest regrets of my career, not winning that game,” he said, “It was a great occasion, a quarter-final at Bramall Lane, full house, one of the best atmospheres I played in. You could really feel the spirit of the cup.

“It was just the disappointment with how it ended really. At the time, we were a division higher and obviously the semi-final would have been at Wembley…”

Then manager Chris Powell had celebrated the fifth-round victory by doing pull-ups – fully suited – on the crossbar in front of the away end at Hillsborough.

“Going up to Hillsborough [against Sheffield Wednesday in the fifth-round] and winning up there was a big moment,” said Jackson. “It was an iconic moment that was. People look back on that warmly when they think about Chris Powell’s time at the club.”

Charlton haven’t got past the third round since, but if they beat Norwich, don’t expect any more crossbar gymnastics.

“I’m not sure I’ll be swinging on the crossbar. I’ll leave that one to Powelly,” said Jackson.