Real Madrid's Gareth Bale tries to kick the ball during their Spanish first division soccer match at El Molinon stadium in Gijon, north of Spain, August, 23, 2015. [Photo/Agencies]

Record chasers

Each goal scored by Lionel Messi and Cristiano Ronaldo will fuel a particular duel.

Both have 77 Champions League goals, tied for the record in the 60-year history of the competition.

The Barcelona and Real Madrid stars also compete during Thursday's draw for the title of UEFA Best Player in Europe for last season. Messi's Barcelona teammate Luis Suarez completes the shortlist of candidates voted by journalists from each of UEFA's 54 member nations.

Chelsea coach Jose Mourinho and Bayern's Pep Guardiola resume their pursuit of a third European title, trying to equal the record of Bob Paisley (Liverpool, 1977, 1978, 1981) and Carlo Ancelotti (AC Milan 2003, 2007; Real Madrid 2014)

Mourinho would be the first coach to win with three different clubs, after Porto (2004) and Inter Milan (2010).

Russia vs. Ukraine

For a second season, UEFA keeps teams from Russia and Ukraine apart.

UEFA made the ruling in July 2014 to avoid fueling tension between the countries during conflict in eastern Ukraine between government forces and pro-Russian separatists.

Shakhtar Donetsk has played home games in Lviv while its home city is a focus of fighting.