The Champions League returns on Tuesday with Cristiano Ronaldo and Lionel Messi competing for yet another prize as the rival stars take aim at the tournament’s all-time scoring record.

Ronaldo and Messi are neck-and-neck in a race to become the Champions League’s all-time leading scorer by breaking the record held by Raul Gonzalez. Ronaldo has 68 goals in Europe’s top club competition, one more than Messi. Raul scored 71.

Ronaldo may have a better chance of getting there first as Real Madrid play at Bulgaria’s Ludogorets in Group B on Wednesday, a day after Messi’s Barcelona have a tougher trip to Paris Saint-Germain in Group F.

The Portugal forward looks primed to increase his goal haul in Sofia after scoring 10 goals in his last six matches, including one four-goal performance and a hat-trick.

Messi, meanwhile, scored his 400th and 401st goals for club and country in Barcelona’s 6-0 rout of Granada on Saturday. Their latest two-man contest comes after they have divvied up the Ballon d’Or for the world’s best player for the past six years and have taken turns leading the Champions League in scoring for the past seven seasons.

PSG meanwhile will be without Zlatan Ibrahimovic who has been ruled out with a left heel injury. Ibrahimovic missed the last two PSG games because of the injury and coach Laurent Blanc says intensive treatment up until Monday morning failed to resolve the problem.

PSG has made a sluggish start to the season, drawing six of nine games so far, and will be without its top scorer against a Barcelona team that has yet to concede a goal. Without Ibrahimovic, Blanc says “it won’t be easy and we know it” because “the opponents are much more attentive when he’s around.”

Uruguay forward Edinson Cavani is expected to lead the attack in his favored center forward’s role.

ENGLISH NEED TO WIN

Liverpool were the only English team to open the Champions League with a win, and only with a last-gasp goal against newcomer Ludogorets. Basel will present a far tougher challenge on Wednesday with striker Daniel Sturridge out injured as Liverpool look to keep pace with Madrid in Group B. Chelsea’s reliance on Diego Costa for goals seemed clear when the striker sat out the 1-1 draw against Schalke in the Group G opener. And ongoing problems with Costa’s left thigh are likely to force him to miss Tuesday’s game at Sporting Lisbon.

“He’s doing almost nothing (in training),” Chelsea manager Jose Mourinho said. “He’s just resting and recovering from the tight muscle he has. Every time he accumulates fatigue.”

Mourinho, who worked at Sporting as assistant to Bobby Robson between 1992 and 1993, is out to end Sporting’s 16-match unbeaten home run in Europe.

Manchester City face a formidable test Tuesday with the visit of a Roma side which has made a perfect start to the season at home and in Europe. It’s been a patchy beginning to the campaign for City, which opened Group E with a loss at Bayern Munich. In Group D, Arsenal host Galatasaray on Wednesday with both Mikel Arteta and Aaron Ramsey out injured.

RUNNER-UP AT RISK

Atletico Madrid were minutes away from winning the European Cup last May before the title slipped away to Madrid. Now after losing this season’s opener, the Spanish league champions face a crucial game on Wednesday when Serie A champion Juventus come to town.

A loss to Juventus, combined with an Olympiakos win at Swedish side Malmo, would leave Atletico six points adrift in Group A. Atletico will be boosted by the return of coach Diego Simeone to the sidelines after he missed the first game due to suspension.

XABI TAKES CONTROL

Bayern travel to CSKA Moscow on Tuesday in Group E with midfielder Xabi Alonso firmly in control of his new team. The Spaniard was only signed at the end of the transfer period after several players went down with long-term injuries. But Alonso stepped right in and has been impressive in directing Bayern’s attack.