The FA Cup is the “greatest cup competition in the world” according to West Bromwich Albion manager Tony Pulis, whose team take on League One Peterborough United in the fourth round this weekend.

A handful of mouthwatering ties are smattered throughout the draw along with three all-Premier League matches. Here are five of the key FA Cup matches to look out for in round four.

Derby County v Manchester United

The fourth round gets underway on Friday when Derby County host Manchester United. Cristiano Ronaldo scored when United knocked Derby out in the fifth round in 2009.

Louis van Gaal is under huge pressure, with José Mourinho reported to be interested in taking over at Old Trafford, and a cup exit could well hasten the Dutchman’s exit from the club.

The cup comes at a good time for Derby, who have seen their Championship promotion challenge falter in recent weeks with successive defeats to Birmingham City and Burnley.

Both managers are likely to rotate their squads. Van Gaal could hand starts to the likes of Juan Mata, Memphis Depay and Jesse Lingard, while Darren Bent, Craig Bryson and Abdoul Camara could come in for Paul Clement’s Rams.

Arsenal v Burnley

Holders Arsenal have what looks a straightforward home tie on paper, but visitors Burnley are flying high in the Championship.

Sean Dyche’s men have won their last three matches, while Arsene Wenger’s side have not won any of their last three games, with their last victory coming in the third round against Sunderland.

Per Mertesacker is suspended for the Gunners after being sent off in the Premier League defeat to Chelsea at the Emirates on Sunday.

Gabriel could come into the back line while Kieran Gibbs, David Ospina and new signing Mohamed Elneny could be in for starts.

Arsenal have won the last two FA Cups and should stay on track for a historic treble with ease, but they cannot afford to underestimate the dangerous Clarets, who boast the Championship’s top goalscorer Andre Gray up front.

Oxford United v Blackburn Rovers

Fantasy football players hoping for FA Cup shocks could be looking at Oxford United’s home game against Championship strugglers Blackburn Rovers as a good opportunity.

Rovers legend Derek Fazackerley, the Lancashire club’s record appearance maker, is the assistant manager of the Us, who are led by former Rovers boss Michael Appleton.

“I’ve got my own connections with the club going back years and years,” said Fazackerley. “It’ll be a wonderful day, but only of course if you go on and win the game.”

Oxford beat Rovers in 1964 in their best ever FA Cup run, when they reached the quarter-finals.

Rovers have found life tough under new manager Paul Lambert and are without a win in seven league games, although they can call upon Scotland international striker Jordan Rhodes, who has hit 11 goals so far this season.

Oxford are on track for promotion from League Two and in Kemar Roofe and Liam Sercombe they have a 23-goal partnership, while Danny Hylton has also contributed six goals.

Portsmouth v Bournemouth

Portsmouth’s home draw against Bournemouth throws up a local derby on the south coast. Bournemouth have had the better of the rivalry in recent years, knocking Portsmouth out of the League Cup in both 2012 and 2013, but Eddie Howe’s side may be more focused on the battle to stay in the Premier League.

League One Portsmouth won the cup back in 2008 but since then financial issues have seen the club slip down the leagues. Under Paul Cook they are looking good for promotion from League Two, but Bournemouth will be strong favourites in this tie.

Record signing Benik Afobe has had a fine start to life at Bournemouth, scoring two goals in his first three Premier League appearances, but Junior Stanislas became the recent Cherries player to join a long injury list when he suffered ligament damage in Saturday’s draw at Sunderland.

Howe made wholesale changes for Bournemouth’s third round win at Birmingham City and he is likely to rotate heavily again, which could provide chances for Adam Federici, Sylvain Distin, Juan Iturbe and Lee Tomlin to impress. Fantasy players should look out for Portsmouth’s Gary Roberts, a set piece specialist who has scored six goals this season, including one in the FA Cup.

Liverpool v West Ham United

Perhaps the most appealing of the all-Premier League ties sees West Ham take on Liverpool.

Both sides may see the FA Cup as their best chance of glory this season, although Liverpool are already be going to Wembley this season after triumphing against Stoke City in the League Cup semi-final on Tuesday.

Slaven Bilić takes his West Ham side to Anfield in terrific form, with the return to fitness of the sublime Dimitri Payet and Enner Valencia having provided a huge boost to the club, who are due to relocate to the Olympic Stadium for next season.

By contrast, Liverpool have been maddeningly inconsistent under Jürgen Klopp, needing a replay to beat Exeter City in the last round, and Bilić may sense it is a good time to play them after the Reds’ tiring exploits on Tuesday, when they had to go all the way to extra time and penalties.

After Carl Jenkinson suffered a bad injury in West Ham’s home draw against Manchester City on Saturday, new signing Sam Byram could get a chance to impress after joining from Leeds United.