Phil Jones
Jones endured a disastrous night against Tottenham Getty

After two wretched performances at the back in their last three games, Manchester United's defence is under the spotlight again.

While Jose Mourinho is also still trying to find harmony in attack following Alexis Sanchez's arrival and with questions arising over Paul Pogba's role in midfield, the manager certainly has a lot on his plate. But with the return of the Champions League, some major flaws at the back need to be addressed quickly.

Phil Jones and Chris Smalling have seemingly been on a mission to outdo each other for mediocrity over the last two weeks. Jones was at fault for Christian Eriksen's 11-second opener in United's defeat to Tottenham Hotspur on 31 January, shortly before he doubled the opposition's lead with an awful own goal past David de Gea.

At St James' Park 11 days later, it was Smalling's turn, penalised for diving before failing to clear the resulting free-kick that led to Newcastle United's winner. He was also incredibly lucky not to concede a first-half penalty.

Smalling is perhaps most at risk of losing his place. United have Victor Lindelof and Marcos Rojo waiting in the wings and Eric Bailly is now poised to return after a three-month lay-off that followed ankle surgery.

United have two very different games over the next seven days; an FA Cup fifth round trip to Huddersfield Town before a visit to the Ramón Sánchez Pizjuán Stadium to take on Sevilla in the first leg of their Champions League last-16 tie. IBTimes UK considers what options Mourinho could use in two fixtures pivotal in their chase for silverware.

Against Sevilla

Mourinho pencilled in Wednesday's first-leg tie in Seville as Bailly's return date. According to ESPN, the manager is keen to have the Ivory Coast international available after the unconvincing displays of his other options over the last few weeks, with the player making steady progress having returned to training last month.

The 23-year-old would seemingly be the manager's preferred option at the heart of defence, but having played no football since November, match sharpness could be an issue. Whether Mourinho takes a risk on him will depend on how much faith he has left in Jones and/or Smalling.

Manchester United vs Sevilla

Rojo is itching to be involved again but Lindelof, a preferred option for Mourinho in Champions League games having started and completed four of the six matches in the group stage of the competition, is a compelling option. Smalling's biggest weakness is the Swede's biggest strength; a defender's ability to find a teammate and support the midfield moving forward is worth its weight in gold in the Champions League and he remains United's best option in this respect, despite still acclimatising to Premier League football.

Against Huddersfield

Lindelof is available at the moment but those calling for the former Benfica star to be immediately brought in from the cold should remember United's last visit to the John Smith's Stadium. It was there he endured his worst performance for the club to date, letting Jonas Lossl's big kick up field drop over him and into the path of Laurent Depoitre to score.

Manchester United vs Huddersfield

United will require a more combative presence against the Terriers, which should take Lindelof out of the equation for now. Despite that harrowing performance at Tottenham, Jones has been United's most consistent operator at the back this season and seems the right fit for what will be another ruck with David Wagner's side.

If effective aggression at the back is to be the order of the day, Rojo, who has declared himself "100% fit" ahead of Saturday's clash, may be the best option to partner Jones. The Argentina international possesses the intensity Smalling still cannot consistently apply to his game despite eight years at Old Trafford and having effectively shackled Depoitre when the two sides met at Old Trafford on 3 February, will likely feel he should be given the nod.