It is 40 years since Ian Porterfield scored, Jim Montgomery somehow saved and Bob Stokoe performed his victory dance across the Wembley pitch and the anniversary is not lost on Sunderland supporter-turned-manager Martin O'Neill. Dreams of emulating that famous win over Leeds United flatlined for an hour at Bolton but they live on, just, courtesy of a stirring recovery from two goals down against the Championship club.

The second-half introduction of Connor Wickham and a stunning equaliser from Craig Gardner gave the Premier League club the reprieve their late efforts deserved. An upset and an inquest into Sunderland's character would otherwise have followed after a lamentable first-half display enabled Dougie Freedman's struggling side to seize control. Lee Chung-yong and Marvin Sordell appeared to have booked Bolton's place in the fourth round until O'Neill went for broke.

"I knew it was going to be difficult but we certainly contributed greatly to our potential downfall," the Sunderland manager said. "We were really sloppy in the first half but a proper third-round tie came to the boil in the last 35 minutes and we did brilliantly to fight back."

The crowd of 12,204 contained 5,000 from Wearside but their impressive appetite for the competition and raucous backing for their team quickly turned to disbelief at Sunderland's amateurish defending, careless distribution and pedestrian attack. Only David Vaughan deserved to be spared the criticism that flowed the visitors' way as they exited at half-time. The goalkeeper Simon Mignolet plus the centre-halves Carlos Cuéllar and Titus Bramble appeared to be spending their first afternoon in the company of a football as their slapstick defending offered Bolton – fielding more changes than Sunderland – constant encouragement.

A dreadful pass across his own penalty area by Cuéllar, put under pressure near his own corner flag by a risky ball from Mignolet, enabled Lee to give Bolton an early lead as the South Korean converted into an empty net from 18 yards with the keeper stranded. The second half warranted a show of fight from Sunderland at the very least but began with yet more poor defending and a second for Bolton when Sordell headed into the bottom corner after Lee's corner was cleared only as far as Keith Andrews, the Wanderers' captain.

The turning point arrived when Cuéllar limped off with a hamstring injury – to the obvious relief of the travelling support – and Wickham joined Steven Fletcher in attack. "He was coming on anyway," O'Neill said. "We would have gone with three at the back."

Andy Lonergan, the Bolton keeper, denied Fletcher three times but was powerless to prevent Wickham giving Sunderland hope with practically his first touch when, after a corner caused mayhem in the box, the England Under-21 international scored his opening goal of the season at the back post.

Sunderland's pressure became unrelenting. Adam Johnson blazed over, Fletcher was thwarted again and eventually, from a short corner rolled to the former Manchester City winger, they were level. Johnson's cross was cleared to the feet of Gardner, who drove into the top corner from 25 yards.

"It's disappointing to lose a two-goal lead," said Freedman. "But overall I am thrilled with the result because we had to show great commitment and desire to defend for our lives and for the first 60 minutes we controlled the game. It was a good Cup tie."