PARIS (AFP) - Avram Grant and Mirko Slomka go into Wednesday's Champions League last 16 second-leg matches knowing that defeat could well mean an end to their reigns at Chelsea and Schalke 04 respectively.

Chelsea entertain Greek side Olympiakos with the tie delicately poised at 0-0 while Schalke take a 1-0 lead to former Champions League winners FC Porto.

The other match of the evening pits Real Madrid against AS Roma with the Italians leading 2-1 from the first leg -- the fourth match between Italian league leaders Inter Milan and Liverpool is next week.

While Chelsea should prevail over the Greek side -- who have never come through against an English team -- Grant is under pressure from both within the squad and without, to deliver a trophy that even his predecessor Jose Mourinho -- "The Magic One" -- failed to produce for owner Roman Abramovich.

However, stories such as that published in the weekend The Observer, hardly augur well for Grant's relationship with the team. Reports said the players snubbed the former Israeli coach three times last week as they conducted an agonising inquest into their insipid display in the 2-1 defeat by Spurs in the League Cup final.

Sean Wright-Phillips for one is determined that the players put on a good display, having slightly atoned for their cup final defeat with a 4-0 humbling of West Ham on Saturday.

"We lost the cup final and we weren't happy with ourselves," the England international told the BBC.

"We know as a team that we can do a lot better and we felt we let ourselves down and especially the fans."

Fortunately for Grant -- whose close friendship with Abramovich would not be enough to save him -- Olympiakos come into the match having suffered two blows: they were toppled from leading their championship at the weekend, and they don't have talented striker Lomama Lualua, who has dislocated his shoulder.

While the Chelsea players have remained silent in terms of going public with their criticism of Grant for fear of incurring the wrath of Abramovich, that has not been the case with Slomka at Schalke.

Schalke suffered their third straight Bundesliga defeat when they were beaten 1-0 at home by league leaders Bayern Munich at the weekend, with fans waving a banner saying: "Mirko Slomka -- no idea, no concept, no confidence!"

A frank 90-minute discussion followed on Sunday between the coach and club president Josef Schnusenberg -- Slomka's biggest public critic -- and failure in Portugal could mean the end of his reign at the Royal Blues.

And Schalke captain Marcelo Bordon is also far from pleased with the situation going into such a crucial European tie.

"Our game last weekend was missing everything, we had no aggression -- that is not the Schalke which I know," Bordon told German agency SID.

Porto -- who Mourinho guided to the Champions League title in 2004 before his spell at Chelsea -- are virtually guaranteed to retain their title as they are 12 points clear of their rivals even after an unimpressive 0-0 draw with mid-table Boavista at the weekend.

Roma travel to Madrid boosted by the fact they are just six points adrift in the league title race after Inter slipped to their first league defeat of the season on Sunday against Napoli.

However, they will be mindful that at the quarter-final stage of the competition last year, they also took a 2-1 lead to Manchester United -- and ended up being trounced 7-1 on the night.

"There's no explanation for that game and it won't happen again," said Roma coach Luciano Spalletti.

That is not to say that Roma are just going to sit back and allow the attacking stars of Real to come at them.

"We can't limit ourselves to defending and trying to stop them scoring. We have to score because we are expecting to have big problems if we try and hold the result at 2-1. They are a balanced side who know how to attack and defend," the Roma coach said.