A look at what's happening in European soccer on Sunday:
Lionel Messi is set for his Paris Saint-Germain home debut against Lyon at Parc des Princes. But PSG coach Mauricio Pochettino will wait until the morning before deciding if Kylian Mbappe is fit to play.
The striker twisted his ankle in the midweek draw against Club Brugge in the Champions League and is having a late fitness test.
PSG's fans are set for their first glimpse of Messi at home after his summer arrival from Barcelona.
Messi came close to his first goal when he hit the crossbar against Brugge.
Lyon has won its previous three matches and coach Peter Bosz has spoken of playing for a win against PSG, which is looking for a sixth straight league victory.
Elsewhere, unbeaten Nice hosts struggling Monaco in the French Riviera derby and second-place Angers takes on Nantes.
Manchester United and Chelsea face tough away games as they seek to stay unbeaten in the Premier League. United heads to West Ham as Cristiano Ronaldo looks to score for the third straight game in his second spell at Old Trafford.
Ronaldo netted twice against Newcastle last weekend and once in the Champions League midweek.
Chelsea visits London rival Tottenham, which won its opening three games in the league before losing at Crystal Palace last weekend. United and Chelsea both have 10 points after three wins and a draw. The other match sees Brighton at home to Leicester.
Valencia's surprisingly strong start under coach Jose Bordalas will be put to its first serious test when Real Madrid rolls into Mestalla Stadium with the Spanish league lead up for grabs.
Bordalas has turned Valencia into a compact bloc led by Carlos Soler.
The midfielder has three goals for his club to go with two more goals in World Cup qualifying for Spain this season. Both sides are one point behind Atletico Madrid at the top of the table.
Madrid will be without the injured Gareth Bale, while Eden Hazard is once again doubtful due to knee pain.
Real Sociedad hosts Sevilla in a clash of sides that aspire to challenge for a top-four finish. Villarreal visits Mallorca seeking its first win of a so far disappointing season. Real Betis hosts the winless Espanyol.
It's a big early season test for both sides when struggling Juventus hosts perfect AC Milan in Serie A. Juventus has just one point from three matches and is desperate for a first league victory in Massimiliano Allegri's return as coach.
The Bianconeri gained some momentum with a 3-0 win over Malmo in the Champions League, while Milan was beaten 3-2 at Liverpool for its first loss of the season. Milan's 39-year-old striker, Zlatan Ibrahimovic, is expected to miss the match with an Achilles injury.
Roma, which has also had a perfect start, visits Hellas Verona, which replaced Eusebio Di Francesco with Igor Tudor as coach after losing three straight. Also, it's: Empoli vs. Sampdoria; Venezia vs. Spezia; and Lazio vs. Cagliari.
In each of Borussia Dortmund's and Union Berlin's previous meetings in the Bundesliga, the home team has won.
Dortmund will need to improve a shaky defense to ensure the trend continues, while Union will hope to deny the home team's fearsome forwards. Erling Haaland already has nine goals in six games across all competitions.
Struggling Stuttgart hosts in-form Bayer Leverkusen, and Wolfsburg welcomes Eintracht Frankfurt.
Frankfurt coach Oliver Glasner is returning to his former club and hasn't had a good start at his new one. Frankfurt has only one point from its first four Bundesliga games. Wolfsburg is the only team with a 100% record.