JONNY Hayes has estimated it would take an investment of around £20 million to enable Aberdeen to bridge the gap with Celtic and challenge for the Ladbrokes Premiership title in future.

But the winger still believes the Pittodrie club can overcome their Parkhead rivals in the William Hill Scottish Cup final at Hampden later this month and finish another successful season on a massive high.

Derek McInnes's side is currently nine points ahead of Rangers at the head of the Premiership table with just four games remaining and is well on course to finish as the best of the rest for the fourth season running.

However, the North-east club is still a massive 27 points adrift of runaway winners Celtic and Hayes sees no prospect of them catching them any time soon.

Asked what it would take to pip them in the league, the Irish winger said: "About £20 million I would say. It's difficult. We know the calibre of players they have.

"They have young players like (Stuart) Armstrong and (Moussa) Dembele. If they improve again and have better seasons than this year again it's going to be a difficult ask. We can't do a lot about that.

"But we can beat them in a one-off game. We lost the League Cup final to them earlier this season because we were really bad that day. On the day of the cup final we didn't show up. The way we played we would have lost to any other team in the Premiership.

"Normally if you lose a game, some individuals have played well. But that day not one player really came off the pitch with any credit. There were a lot of sloppy mistakes. There were a million and one reasons, but it's hard to pinpoint what exactly went wrong. It could have been more than three, if we are honest.

"But we know we are a lot better than we showed that day. The Scottish Cup final is a one-off game and if we play to our best that's all we can do. Celtic have proven they are the best team in the country, but we have had a couple of tight games against them this season.

"It's up to us to give a better account of ourselves this time and do the best we can. The manager is adamant it's on the back burner until the league is over. Hopefully the lads can do well and play their way into the cup final team."

Rangers were expected to claim second spot in the league this season due to the fact they have a far larger playing budget than Aberdeen.

But Hayes, who has been nominated for the PFA Scotland Player of the Year Award by his fellow professionals, is believes his side deserve to be runners-up once again and can improve further.

"If we have the natural progression we know is within us we can go on and try to finish second and get closer to Celtic," he said.

"It will be tougher again next season. Rangers will invest. So, too, will Hearts in what will be their new manager’s first full season.

"But in the last few years it has only got tougher and our manager has risen to that by signing better players and getting even more out of the players he already has at the club every week.

"Our manager has put it across we must finish as strongly as possible with the battle for second and if we manage to achieve that it will be a definite improvement on the last few years."