Old foes Manchester United and Arsenal will renew their rivalry at Old Trafford on Thursday in what's expected to be a cracking encounter.While Manchester United got off to a flying start to the 2021-22 Premier League season, Arsenal suffered greatly in the opening weeks. But their fortunes have altered considerably over the past couple of months. Arsenal are currently sitting fifth in the Premier League table with 23 points in 13 matches.Meanwhile, Manchester United have slipped to eighth with just 18 points so far. The Red Devils have lost five of their last eight matches in the Premier League and have won just a single game in that time. The appalling dip in form led to the sacking of Ole Gunnar Solskjaer.Manchester United@ManUtdℹ️ Michael Carrick will remain in caretaker charge for Thursday's #PL clash.#MUFC | #MUNARS3:58 AM · Nov 30, 2021196481994ℹ️ Michael Carrick will remain in caretaker charge for Thursday's #PL clash.#MUFC | #MUNARSRalf Rangnick has been appointed interim manager for the rest of the season but he won't be in the dugout on Thursday night. Michael Carrick will be in charge for this one. Arsenal have four wins in their last five and it definitely looks like Manchester United will have their work cut out against their rivals.Without further ado, let's take a look at five reasons why Manchester United will struggle against Arsenal.#5 Manchester United's poor recent record against ArsenalManchester United v Arsenal - Premier LeagueUnder Ole Gunnar Solskjaer, Manchester United had maintained a good record against the Premier League top 6 up until this season. However, Arsenal have been a side that they've just not been able to get the better of in recent times.The Red Devils are winless in their last six Premier League meetings with the Gunners. They have lost three and drawn three. Manchester United's last win against Arsenal came all the way back in April 2018.Arsenal, particularly under Mikel Arteta, have been a tough cookie to crack as far as Manchester United are concerned. Given United's current form, there is no reason why Thursday night should be any different.#4 Arsenal solid enough defensively for Manchester UnitedArsenal v Norwich City - Premier LeagueManchester United were one of the best attacking teams in the Premier League last term. However, they have been nowhere near their best in recent weeks.Manchester United have scored just five goals while conceding 12 in their last five Premier League matches. Three of those five goals came against a hapless Tottenham Hotspur who were still being managed by Nuno Espirito Santos.Arsenal have kept six cleansheets in the Premier League this term. They have kept three cleansheets in their last four games with the only exception being a 4-0 loss against Liverpool. But the Manchester United attack is currently nothing like the Liverpool one and the Gunners ought to be able to hold their own on Thursday.Fantasy Premier League@OfficialFPLArsenal's back line are feasting 🍽It's a third clean sheet in four matches and Tomiyasu and Tavares picked up assists!#FPL #ARSNEW6:29 AM · Nov 27, 20211890110Arsenal's back line are feasting 🍽It's a third clean sheet in four matches and Tomiyasu and Tavares picked up assists!#FPL #ARSNEW https://t.co/dyYUVeUBRc