The focus will be on Juan Mata when he makes his Manchester United debut on Tuesday, although a relic from the club's golden past is heading to Old Trafford looking to steal the spotlight from the Spain midfielder.

Ole Gunnar Solskjaer played a central role in United's trophy-laden era under former manager Alex Ferguson, famously scoring the winning goal in the 1999 Champions League final against Bayern Munich.

It should ensure Solskjaer receives a rapturous welcome when he returns to United as manager of Cardiff, but home fans will be less impressed if he guides the Welsh team to victory in a Premier League match that is crucial to both clubs

United need a win to revive their chances of finishing in the top four and making next season's Champions League. Cardiff, which are in last place, require three points in their battle to avoid relegation.

Here are five things to know about the upcoming round of midweek Premier League games:

MATA'S DEBUT

Three days after completing his club-record move to United from Chelsea for 37.1 million pounds ($61.2 million), Juan Mata will be wearing the famous red shirt for the first time against Cardiff.

The playmaker hasn't played since being substituted in the second half of Chelsea's 3-0 win at Southampton on January 1, but that won't stop United manager David Moyes from either starting Mata or bringing him on off the bench.

"Juan's not too far away from (full) fitness," Moyes said. "I know he has missed a few games and maybe not started quite as many games as he'd have liked, but I'd like to get him involved against Cardiff."

The last time Mata played at Old Trafford, he scored the winning goal for Chelsea in their 1-0 victory in May.

SOLSKJAER RETURNS

Despite his rich history with Man United, there'll be no divided loyalties for Ole Gunnar Solskjaer when he makes his return to Old Trafford.

"I looked at when we were scheduled to play Manchester United the day I got the job, but I've been so busy since then that I've not had time to think about it," said Solskjaer, who scored 126 goals in 266 appearances during his 11 years at United from 1996-2007.

"I'll go there and of course I'll enjoy it, but I'm not thinking about all the surroundings, I'm thinking about my team. We need to go out there, enjoy it and play the best we can against the best club in the world."

Solskjaer began life at Cardiff with an FA Cup win at Newcastle at the start of the month, but has lost both of his Premier League games in charge of the Welsh club - against West Ham and Manchester City.

Cardiff are last on goal difference.

HANGING IN THERE

Manchester City and Chelsea have found their top gear in recent weeks in the Premier League, but Arsenal are still out in front with 16 games remaining.

Arsene Wenger's sides have been famous down the years for their silky passing and attacking style, yet it is gritty defensive work that is the platform for Arsenal's charge for the title.

Since losing 6-3 to Man City on December 14, Arsenal have kept six clean sheets in eight matches - seven of which have resulted in wins.

"If you look at successful Arsenal sides of the past, they have all been built on a strong back four and a good goalkeeper," Arsenal right back Carl Jenkinson said. "It is important we have that as a building block."

Arsenal hold a one-point lead over City, and are two clear of Chelsea, ahead of a match at Southampton.

RED-HOT AGUERO

Maybe the golden boot in the Premier League isn't sewn up, after all.

Liverpool striker Luis Suarez has been in unstoppable scoring form this season with 22 goals in just 17 games, leaving many to predict that the Uruguay international will easily finish the season as the division's top scorer.

Sergio Aguero may have something to say about that.

The Man City striker has scored six goals in four games across 11 days since returning from a month out with a calf injury. Next in his sights is Tottenham on Wednesday.

With 14 Premier League goals to his name, there is still a chance Aguero could catch Suarez.

"The important thing is the goals contribute to the team's victory, the team wins and we win titles," Aguero said. "I don't have any specific goals to reach, but (to score) as many as possible."

MERSEYSIDE DERBY

Just one point separates Liverpool and Everton as they meet for the 222nd Merseyside derby, with both teams battling to finish in the Champions League positions.

Liverpool occupy fourth place, but are facing a real fight from Tottenham - which are level on 43 points - and Everton. Man United are six points behind Liverpool but have been given a major lift with Mata's signing.

Everton have already beaten United and Chelsea this season, as well as drawing at Arsenal. It was also a minute away from beating Liverpool at Goodison Park in a classic derby in November, only for Daniel Sturridge to score and earn Liverpool a 3-3 draw.

"To win at Anfield would be just another statement win," Everton goalkeeper Tim Howard said, "but, to be honest, even if we beat Liverpool we will still probably be under the radar, and I think that suits us."