Borussia Dortmund have fitness concerns over a trio of players ahead of Saturday's Bundesliga match against struggling Stuttgart.
Jurgen Klopp's men are a point ahead of local rivals Schalke following the goalless draw when the teams met at the Westfalenstadion in midweek.
However, Lukasz Piszczek, Roman Weidenfeller and Pierre-Emerick Aubameyang are all doubts ahead of Saturday's trip south.
Klopp claimed right-back Piszczek's muscle problem is "more than just a niggle" and has hinted that Kevin Grosskreutz could step in this weekend.
However, the Dortmund boss is more hopeful about striker Aubameyang and goalkeeper Weidenfeller, hoping both recover from cold symptoms in time to figure as he seeks to maintain his team's advantage over Schalke, who tackle Hertha Berlin at the Veltins Arena on Friday night.
Wolfsburg's quest for Champions League football next season continues with a home game against Eintracht Frankfurt.
Dieter Hecking's men won 3-1 against Werder Bremen last time out and the manager said: "We are more stable and disciplined in working against the ball.
"If we can improve our game going forward, we are capable of beating many opponents - but that's something we need to do."
Fellow champions League hopefuls Bayer Leverkusen are at home to Eintracht Braunschweig, whose focus is on events at the other end of the table.
Braunschweig's hopes of survival were improved with a 3-1 victory over Mainz in midweek, their first in six matches.
Defender Ermin Bicakcic is not giving up hope. He said: "We've got to keep on fighting and believe we can beat the teams at the top."
Survival is also on the agenda at the Mage Solar Stadion, where 15th-placed Freiburg and 14th-placed Nurnberg meet hoping for a success which will move them further clear of the danger zone.
Nurnberg ended a run of four successive defeats with a 2-0 victory over Stuttgart in midweek and goalkeeper Raphael Schafer admitted: "After the four defeats, we had a lot of soul searching to do.
"However, we're still a way off safety and we have got to play the way we did against Stuttgart at Freiburg."
Elsewhere on Saturday, champions Bayern Munich face Hoffenheim, while mid-table rivals Mainz and Augsburg meet at the Coface Arena.
Sunday's games see erratic European hopefuls Borussia Monchengladbach tackle relegation-threatened Hamburg, while Hannover and Werder Bremen, who clash at the HDI-Arena, have each lost their last two games and still have relegation fears with five matches remaining.