What to watch in the leading soccer leagues in Europe this weekend:
Another new era starts for Manchester United on Saturday, and the club is looking to the future by returning to the past.
Ole Gunnar Solskjaer, United's popular former striker who scored the winning goal in the 1999 Champions League final, replaced the fired Jose Mourinho as manager until the end of the season and takes charge of his first game at Cardiff.
Solskjaer is the fifth coach to take either permanent or temporary control of United since the retirement of long-serving Alex Ferguson in 2013.
Cardiff, which fired Solskjaer in 2014 after an ill-fated nine months in charge, has won four of its last five home games. United is 11 points off the top four in the race for Champions League qualification, and 19 points behind first-place Liverpool.
The leaders will look to reach Christmas unbeaten when they travel to Wolverhampton Wanderers on Friday. Manchester City, which is a point behind in second, hosts Crystal Palace on Saturday.
— By Steve Douglas
With five goals in his last two Spanish league matches, Lionel Messi will aim to keep up his impressive recent scoring run when Barcelona hosts Celta Vigo on Saturday. Messi tops all scorers in the competition with 14 goals through 16 rounds.
Barcelona leads La Liga by three points over both Sevilla and Atletico Madrid and is looking for a fourth straight clean sheet.
Atletico hosts Espanyol, which has lost five straight games, and Sevilla visits Leganes on Sunday without top scorer Pablo Sarabia and playmaker Ever Banega because of an accumulation of five yellow cards.
Real Madrid's match against Villarreal has been postponed until Jan. 3 as it competes in the Club World Cup in the United Arab Emirates. Madrid faces Al Ain in the final on Saturday.
— By Joseph Wilson in Barcelona
The top two teams meet in the Bundesliga's final round before the winter break with Borussia Moenchengladbach visiting Borussia Dortmund on Friday.
The game has been given added spice after lost its first league game of the season on Tuesday, giving second-place Moenchengladbach the chance to move within three points with a win.
Dortmund defenders Manuel Akanji, Abdou Diallo and Dan-Axel Zagadou are all out injured. That could play into the hands of Gladbach forwards Thorgan Hazard and Alassane Plea, who both have nine league goals.
Dortmund coach Lucien Favre will also be facing one of his former teams. Under Favre from 2011-15, Gladbach went from surviving relegation to qualifying for the Champions League.
Defending champion Bayern Munich, tied for points with Gladbach, visits Eintracht Frankfurt on Saturday.
— By Ciaran Fahey in Berlin
Juventus' Cristiano Ronaldo has scored five goals in five games against Roma during his career and he'll face the crisis-hit club again at home on Saturday.
Roma, which hopes to welcome back striker Edin Dzeko from injury, has lost its last eight matches at Juventus and trails the undefeated league leader by 22 points.
Its unconvincing victory against Genoa last weekend brought an end to a five-match winless streak, but a heavy loss at Juventus would pile more pressure on coach Eusebio Di Francesco.
Juventus has an eight-point advantage over second-placed Napoli, which hosts Spal. Inter Milan is third, 14 points below Juventus, and travels to last-place Chievo Verona.
All 10 Serie A matches will take place on Saturday.
— By Daniella Matar in Milan