As reported by The Scottish Sun, Rangers chief Dave King and Managing Director Stewart Robertson have promised investment is on the way to Ibrox this summer in support of Pedro Caixinha.

Securing the Portuguese is a vital step in revitalising the club after a tough season but it will mean little if he is not backed up in the upcoming transfer window. The new boss needs the opportunity to assert his own personality on the playing squad and bring in players that can play to his preferred style.

Whether they come from Scotland or further afield, Caixinha needs to bring players he trusts to get the job done.

This could well turn out to be one of the most important transfer windows at the club in recent memory. More poor recruitment will almost certainly gift Celtic 7-in-a-row and take resources out of Rangers that are already stretched thin as it is.

With all that in mind, these are the FOUR Caixinha signings that could transform this Rangers side...

Rashid Sumaila

Rashid Sumaila is a Ghanain international who was one of Pedro Caixinha's most trusted players at former club Al-Gharafa. A central defender with committed tackling skills and a strong physical presence, he is out of contract with parent club Al-Qadsia at the end of the season.

He has won 6 caps for his country and in 2011 won the ' Best Defender Award' with the Ghana Football Association.

This is an area of the team that Rangers badly need improvement in with the likes of Rob Kiernan just not getting the job done this season. With Clint Hill also ageing, the Ibrox side could do with some fresh blood in the heart of defence.

At 24, Sumaila has his whole career ahead of him and also the trust of his former boss Pedro Caixinha.

Vladimir Weiss

Another former Pedro Caixinha player, Vladimir Weiss is of course well known to Rangers fans after a successful loan spell at the club in 2010/11 from Manchester City. Weiss has forged a decent career for himself since leaving Ibrox, representing his country 58 times and spending time La Liga, Serie A and the Greek top-flight.

He's now plying his trade at Al-Gharafa, signed by Pedro Caixinha in January 2016. He's had a storming spell at the Qatari club and this season has 10 goals in 18 matches.

Could a reunion be on the cards with a return to Glasgow? We know he's still a big fan of the club, regularly taking to social media to cheer the team on from afar in big games.

Ryan Tunnicliffe

Ryan Tunnicliffe is a former Manchester United youngster, once tipped as a future Old Trafford first teamer after winning their Young Player Of The Year award. However he didn't quite make the grade there and left for Fulham in 2014.

He has over 150 Championship appearances to his name, showing he has the first team experience required to make an impact at Ibrox, and at 24 still has his best years ahead of him.

Currently on loan at Wigan, his contract with parent club Fulham is up this summer and unlikely to be renewed. That opens the door for a club like Rangers to offer decent wages and the chance to become a hero with one of biggest fan-bases around.

A central midfielder, he'd add vital quality and depth to the position, with the area currently being filled by loan stars and players in underwhelming form.

Jason Cummings

Jason Cummings is a fine goalscorer who is just waiting for his chance to make an impact in the Scottish Premiership. With 68 goals in 142 appearances for Hibernian, he's shown he has the nous to find the net in Leith, sometimes even against Rangers themselves.

Still just 21, he's tipped for big things in the game and if the likes of Rangers, or even Celtic, don't move for him then he's likely to try and forge a career down in England.

Letting his talent leave Scotland would be a great shame and Rangers should turn to him to fill the role of the ageing Kenny Miller, a man you'll remember was also initially signed from Hibs.

Can he be their new talismanic striker? He has every chance and the Gers should at least explore the option.