Berlin - With Bayer 04 Leverkusen and Hertha Berlin embroiled in fierce battles at either end of the table, Matchday 19's showdown between the two sides at the Olympiastadion is a must-win encounter for both teams (kick-off 19.00 GMT / 20.00 CET).

bundesliga.com previews what could be a pivotal clash in the battle for the top four and the relegation dogfight...

Hertha's 2-0 defeat to Werder Bremen on Matchday 18 was marked by a 'lack of aggression', according to coach Jos Luhukay, and meant that his side slipped to within a place of the relegation zone. The heat is also on for Leverkusen, however, whose 0-0 home draw with Borussia Dortmund left them a point off their competitors in the chase for a top four finish.

After the Bremen loss, Luhukay claimed there 'will be changes' for the visit of Leverkusen. Peter Niemeyer received the medical 'green light' this week and could return in midfield, but young defenders Nico Schulz (r.) and John Anthony Brooks are likely to watch from the bench. Salomon Kalou is still at the AFCON, while key midfielder Per Skjelbred is suffering from scarlet fever.

After coming off in the 69th minute with an achilles problem in the Dortmund draw, Leverkusen forward Josip Drmic's (l.) participation in the capital is in doubt. With Heung-Min Son still away and Robbie Kruse injured after the AFC Asian Cup, coach Roger Schmidt has a selection headache in attack, while young full-back Tin Jedvaj remains sidelined with a thigh complaint.

Though defeat in Bremen was tough enough to take for the travelling Hertha fans, seeing their side muster only three shots on goal was further cause for concern. In Kalou's international absence, however, the onus falls on Julian Schieber (r.), who netted in the 4-2 loss in Leverkusen on Matchday 2, to rediscover his shooting boots.

In a game marked by both sides' relentless pressing, Hakan Calhanoglu's creative instincts were somewhat stifled in the draw with Dortmund, leaving the youngster struggling to impose himself. However, the Turkish international will be licking his lips at the prospect of facing a defence which has leaked 14 goals in its last five games.

Jos Luhukay, (Hertha Berlin coach, r.): "We need more confidence and self-belief. I was disappointed by the goals we conceded in Bremen and there will be changes."

Roger Schmidt, (Bayer 04 Leverkusen coach): "It's going to be a tough game. Hertha have been very strong at home this season and we will have to take our chances."

Hertha have only picked up one win in their last five games, but Leverkusen coach Schmidt (l.) does have a point when highlighting their home strength: Both Dortmund and VfL Wolfsburg have already lost at the Olympiastadion this term. For their part, die Werkself's 0-0 draw with BVB leaves them with seven wins in 18 games, the club's worst return for nine years.

Leverkusen are unbeaten in the last seven games against Hertha, while die alte Dame's last win in this fixture came as long ago as March 2009. In another ominous sign for Wednesday's hosts, Luhukay has never beaten Leverkusen in six attempts as a Bundesliga coach, including the 4-2 defeat at the BayArena in August.

Possible line-ups:

Hertha Berlin: Kraft - Pekarik, Lustenberger, S. Langkamp, J. van den Bergh - Hosogai, Haraguchi - M. Ndjeng, Stocker, Beerens - Schieber

Bayer 04 Leverkusen: Leno - Hilbert, Toprak, Spahic, Wendell - L. Bender, Castro - Bellarabi, Calhanoglu, Brandt - Kießling

Click here to find your local broadcaster for this match