Manchester United have a rich history with signings from the Portuguese top-flight. The likes of Cristiano Ronaldo and Nani earned their stripes while playing at Old Trafford under Sir Alex Ferguson. However, they were not the only two signings to have come from the Primeira Liga. Ferguson recognized potential in all the countries he scouted and Portugal was no different.When the Scotsman signed Ronaldo from Sporting Lisbon, the forward was still a kid. It was under Ferguson that Ronaldo found a foothold in world football. Ferguson found similar gems in Portugal, whom he brought to England and then developed them into stars that could give him success in the longer run.Manchester United have always scouted Portugal for signingsFerguson's successors have traveled a similar route. Bruno Fernandes' recent success at the Manchester-based club is yet another example of how good the country is at producing top footballing talent.However, not all have managed to succeed. The likes of Bebe have found the move to Old Trafford too big to handle and have faded into oblivion. Even more recent players such as Marcos Rojo and Diogo Dalot failed to settle down well in England.In this article we are going to list five of Manchester United's best signings from the Primeira Liga in Portugal.#5 AndersonMK Dons v Manchester United - Capital One Cup Second RoundSome might question the inclusion of Anderson on this list but the Brazilian was one of the brightest talents in world football when he joined Manchester United.Manchester United paid a fee in the region of €30m to Porto for his services, making him one of their most high-profile signings back in 2007.🇧🇷 There was no stopping this Anderson strike ☄️#MUFC #GoalOfTheDay pic.twitter.com/M1A2jdoUEE— Manchester United (@ManUtd) February 15, 2021He was initially rejected a work permit but it was granted later because of the exceptional talent he would bring to the Premier League.Anderson was given a role similar to the one at Porto, just behind striker Wayne Rooney, but eventually settled into a deeper role.It wasn't without any reason that Sir Alex Ferguson trusted Anderson with a spot-kick in the UEFA Champions League final against Chelsea in May 2008, one that he calmly converted. Anderson ended the season with as many as 38 appearances overall, setting up two goals for his team-mates.However, an injury prevented him from excelling even further heading into his second season at Old Trafford. Anderson failed to fulfill his potential, but he still enjoyed considerable success in terms of silverware at Manchester United after arriving from the Primeira Liga.Before leaving Manchester United, Anderson notched up 181 appearances, scoring nine goals and setting up 21 more for his team-mates.#4 NaniManchester United v Liverpool - Capital One Cup Third RoundThe summer of 2008 saw Manchester United showing much activity in the transfer market, bringing in a number of new signings to strengthen their existing squad. Nani was one of the most exciting signings made, arriving from Sporting Lisbon.The Portuguese cost the Red Devils a fee in the region of €25m and he quickly developed a strong partnership with his new team-mates Ronaldo and Rooney.Nani was one of the primary weapons in Sir Alex Ferguson's arsenal. He was perfectly suited to the Scot's counter-attacking football, often catching the opposition off guard. With Ronaldo in his side, Nani developed a formidable combination, giving further ferocity to Manchester United's wing-play.Prior to Ronaldo's departure in 2009, Nani went on to win successive Premier League titles at Manchester United alongside his fellow Portuguese.Exactly 6 years ago @ManUtd announced that Sir Alex was going to retire. What an emotional day I will never forget. Thanks for everything Boss!#manutd #throwback #boss pic.twitter.com/jCtbbTBoVk— Nani (@luisnani) May 8, 2019Nani stayed on until 2015, winning two more league titles before his eventual departure. He was also part of Manchester United's Champions League winning squad back in 2008.His figures for Manchester United mount up to 41 goals and 73 assists in 230 appearances. Undoubtedly, he remains one of Manchester United's most successful signings from the Portuguese league.