Portsmouth are sweating on the fitness of Liam Lawrence, who limped out of Saturday's 1-0 win over Barnsley with a recurrence of a calf injury.Jonathan Hogg, available after a ban, could play if Lawrence is ruled out. [LNB]Palace will check on Alex Marrow, who has been struggling with an ankle problem and failed a fitness test ahead of the game against Sheffield United. [LNB]Nathaniel Clyne is playing despite an ongoing knee problem, which has restricted his training. [LNB][LNB] MATCH PREVIEW Fresh from winning their proverbial six-pointer at home to Sheffield United on Saturday, Crystal Palace will look to take another step away from the bottom three when they visit Portsmouth. [LNB]Palace's weekend victory took them five points clear of United, leaving the Yorkshire side entrenched in the relegation zone. It also stretched the Eagles' recent good run - they have lost only one of their last six matches. [LNB]A victory on Tuesday would take them to within one point of troubled Portsmouth, who eased their own relegation fears with a 1-0 victory against Barnsley last time out, courtesy of Kanu's late header. [LNB]That win - their second in succession - was a major boost for Pompey, as was the performance of on-loan forward David Cotterill. The Wales international made an impressive home debut and could be a key player in the coming weeks. [LNB][LNB] MATCH FACTS Head-to-head[LNB]• This is the 50th league encounter between these clubs. Palace have won 18 and Portsmouth 13 of the previous 49. [LNB]• Palace have won only one of their last eight league and cup matches against Pompey. [LNB]Portsmouth[LNB]• A victory for Portsmouth would see them win three in a row for the first time since October. [LNB]• Only 143 of Portsmouth's 321 goal attempts this season have been on target. At 43%, it is the poorest ratio in the division. [LNB]• Aaron Mokoena is standing by for his 150th league appearance. [LNB]• Hayden Mullins and Hermann Hreidarsson could both face their former club. [LNB]Crystal Palace[LNB]• Palace have won two, drawn three and lost one since Dougie Freedman took permanent charge. [LNB]• The Eagles have the worst away record in the the second tier, with one win, three draws and 12 defeats, and 37 goals conceded. [LNB]• They have only picked up one point from eight away matches against current bottom-half clubs. [LNB]• Palace have failed to score in 14 Championship matches this season - more than any other team.