Tranmere boss Micky Mellon labelled his side’s 2-1 FA Cup victory over Watford as a “massive achievement” as they prepare to take on Premier League giants Manchester United in the next round.

Super-sub Paul Mullin came off the bench to be the 104th-minute hero when he headed the ball past Daniel Bachmann to cause ecstasy in the home stands.

The League One side were dominant throughout much of the contest and got their reward when centre-back Manny Monthe finished from close-range in the 36th-minute.

Watford hit back after the interval, substitute Kayden Hinds smashing past Davies after a scramble in the hosts’ penalty area.

After two games and over 210 minutes of football altogether, the tie was finally put to bed when Mullin popped up in the right place at the right time nod the ball home.

“It was massive for a whole host of reasons. I can’t underestimate how big a result and performance it was because now we are able to say that Manchester United are coming to Tranmere on Sunday,” Mellon told the press.

“To be able to bring that to the local community and to the fans is huge. You guys have stood here [journalists] and we have had some really tough times but tonight was brilliant.

“I loved how Tranmere showed its muscle once again as a big football club, you only have to look at the terraces and think that it could really take off here.

“But to get results like this for a team that was in the National League three years ago is a massive achievement.

“Of course, we understand the league position but we will build on the performance tonight.

“I think that we have been building on it for a few weeks now, you have seen the quality of the lads that have come in and how they have moved things ahead and that was important.”

That is now three goals in five games for Monthe. The centre-back found himself on the scoresheet in Rovers’ fightback at Vicarage Road as well as a consolation in Tranmere’s last home outing against Ipswich.

Mellon also went onto hail the performance of the old members of the squad, but it was the 24-year-old who nonchalantly guided his left-footed strike in off the post to give Tranmere a much-deserved opener.

“He is prolific, isn’t he?” Mellon chuckled.

“He should do more, six feet four and built like the proverbial. I thought he was brilliant tonight, but Peter [Clarke] beside him was unbelievable.

“What a performance from him at 37 years of age, [Neil] Danns, 37 years of age, [David] Perkins, 37 years of age.

“I was delighted for them and going into extra-time they were the strongest players.”

A hectic schedule of Premier League action meant that Nigel Pearson picked a much-changed side that fell to a last-gasp Tyrone Mings winner at Villa Park on Tuesday night.

However, you could take nothing away from the classy performance Tranmere put out in difficult conditions at Prenton Park.

Corey Blackett-Taylor had two wonderful chances to put the hosts ahead inside the opening half-an-hour. The winger’s left-footed shot sailed over before he failed to direct a rebound from Kieron Morris’ shot goalwards.

Despite their dominance, Tranmere struggled to find that elusive second goal and could have put the game to bed in normal time. Danns went close before Mullin failed to guide his shot on target after some excellent work in the Watford box.

“From the first minute to the last, I thought we were brilliant,” said Mellon.

“I really enjoyed watching us. We have been performing like that it patches and maybe just switched off a little bit defensively at times.

“However, tonight, it was a terrific performance from start to finish and the most disappointing thing was conceding from a set-play, but I can’t complain too much about that.”