The German champions host holders Real in a crunch clash of European powerhouses at the Allianz Arena with the return leg on May 1 in Madrid.
Two of this season's deadliest goalscorers will go head-to-head when Ronaldo, with 42 goals in 39 games, faces Lewandowski, who has scored 39 times in 43 matches.
Much of the pre-match focus has been on Ronaldo, who has scored 15 goals and hit the net in each of Madrid's 10 Champions League games this season.
Ronaldo has scored nine goals in six games against Bayern, including five over two legs when Real won 6-3 on aggregate in last season's quarter-finals.
James has shone at Bayern since leaving Real on a two-year loan deal last July at the end of three often difficult seasons in Madrid.
Zidane's appointment as Madrid coach in January 2016 was a setback for James as the Frenchman gave him limited opportunities and often left him on the bench.
Real midfielder Toni Kroos, who won the 2013 treble of Champions League, Bundesliga and German Cup titles with Bayern, says the Spaniards are hungry for a third straight European crown.
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