Atletico Madrid's transfer ban meant that Antoine Griezmann became a no-go, Andrea Belotti was looked at and Real Madrid's Alvaro Morata was also heavily linked.
The out-of-favour forward has fallen down Zinedine Zidane's pecking order and quickly became United's number one target. After negotiations slowed and then stalled, however, an agreement could not be reached and the Reds were forced to look elsewhere.
Last week's announcement that a deal had been reached for Everton's Romelu Lukaku - who looked set to move back to Chelsea - came out of the blue and wasn't a move that we saw coming. The deal has now been confirmed and Lukaku will be a Manchester United player next season.
The 24-year-old Belgian forged an impressive goalscoring record at Everton that is difficult to argue with but the question is whether he can transfer that form in front of goal at Old Trafford. Everton played to his strengths and he became the focal point of their attack, but his style of play is different from anyone we've had up front for a while.
Whilst the Belgian doesn't have the technical qualities of a Morata or a Griezmann, he's quick, powerful, plays "on the shoulder" and is at his best running in behind.
All valuable assets for a proven Premier League striker - which Lukaku certainly is - but is that alone good enough to shine on the biggest stage he now finds himself on?
With a huge £75 million price tag, a club with an expectant global fanbase and a demanding, high-profile manager, Lukaku will need to prove he has the temperament to deal with the added pressure. Morata, although older than Lukaku, looks a better fit for the tactical and technical challenge the Champions League will bring.
In the past three seasons, Lukaku has made 36 league appearances against Chelsea, United, City, Arsenal, Spurs and Liverpool and has scored just five times. His perhaps unfair reputation as a "flat track bully" marks him out for criticism, but a failure to beat those so called "lesser" sides last season - particularly at home - proved United's chronic undoing.
A master exponent of turning draws into wins against those lesser lights could be exactly what we need to challenge for a Premier League title. Then again, having paid £75m on a striker, the expectation will be for Lukaku to add big game goals to his repertoire of undoubted talent.
Is he good enough for a club of United's size and stature?
Time, ultimately, will tell.