They may be the fiercest of rivals, but both Liverpool and Manchester United are going through similar seasons of rebuilding. Here are five similarities between the two English Premier League (EPL) giants this season:

1. Slow starts that had fans worried

Liverpool were fresh from last season's second-place finish, and Reds fans were optimistic for another tilt at the EPL title even though the club have sold serial biter Luis Suarez to Barcelona.

But all title talks were shelved when Daniel Sturridge suffered a long-term injury. Without a potent strikeforce to finish off their neat build-ups, Liverpool suffered numerous defeats to tumble to mid-table mediocrity around November.

Likewise, Manchester United fans were optimistic that, with new manager Louis van Gaal, they could instantly make an improvement from last season, when they finished seventh under the sacked David Moyes.

But they had to wait until United's fourth league match before they can even enjoy a win. By then, doubts were already sown about van Gaal's managerial skills.

2. Misfiring strikers

Mario Balotelli and Radamel Falcao were well-known throughout Europe for their goal-poaching expertise. So when the Reds signed the enigmatic Balotelli, and the Red Devils got the explosive Falcao on loan, fans were excited at the prospect of seeing great strikers scoring great goals for their clubs this season.

Sadly, that scenario failed to materialise for either club. Balotelli has scored just once in the EPL this season as he fell dramatically down the pecking order among the Liverpool strikers.

Falcao, meanwhile, struggled to hold down a regular spot in the Man United starting line-up. His explosiveness was hampered by injuries, and he nabbed just four EPL goals, much to the disappointment of the United fans.

3. Awful defence

Usually, both Liverpool and Man United can rely on steady defenders. But this season they were instead hampered by comical defending all around. Dejan Lovren was a big signing for the Reds, but struggled mightily to justify his price tag with a series of howlers earlier in the season.

And most of the United defenders - Phil Jones, Jonny Evans, Chris Smalling and Rafael da Silva - had a really tough time understanding van Gaal's three-man-defence system initially. It was only after Daley Blind came on board that van Gaal was able to stabilise the jittery defence and start winning.

4. Unorthodox formations

Both Liverpool manager Brendan Rodgers and United boss van Gaal are unafraid to trot out teams with outlandish formations to find the best systems for their sides to win.

As Rodgers struggled with injuries to his strikers and a porous defence line, he struck upon a unconventional 3-4-3 formation that suddenly solved his dual problems. The Reds have not lost a league match in 2015, just as his side got comfortable with that formation.

Meanwhile, van Gaal also demanded that Man United - who have usually played 4-4-2 during Alex Ferguson's 25-year tenure - play in his 3-5-2 system. However, the results have been less spectacular, as United struggled for fluency even as they became a tough side to beat.

5. Still something to fight for

Despite the poor starts which cost them any shot at challenging Chelsea for the EPL title, the two sides still have a lot to play for this season. Manchester United are desperate to land a Champions League qualifying spot after missing out this season, and so will be eager to fend off Liverpool from fourth place in the league.

Liverpool, on the other hand, hope to send off captain Steven Gerrard to the United States with an FA Cup win on his birthday. Can they do it? They will need to get past Blackburn, Aston Villa and likely Arsenal to do so.