Barca conceded a late equaliser at Espanyol last weekend which, coupled with Real's 5-1 mauling of Granada, saw Jose Mourinho's side open up a clear gap at the top of the table.
That could increase to eight points over the weekend, for 24 hours at least, with Real travelling to 14th-placed Mallorca on Saturday and Barca hosting Real Betis on Sunday evening.
The teams will also meet in the first leg of the Copa del Rey semi-final at the Bernabeu on Wednesday, with Mourinho's team currently producing breathtaking attacking football that has seen them score 61 goals in 17 league games.
However, Mascherano refuses to contemplate conceding the league and concentrating on the Champions League and Copa del Rey with 21 games still to play.
He told reporters at a press conference: "No, I don't know who (thinks that) but we think not. In order to continue advancing in the Champions League you have to maintain a good level in the league.
"If you are at a good level you will advance. It (five points) is a difference we would like, but we have 63 points to play for and in this game anything can happen."
Mascherano also paid tribute to Wednesday's opponents, saying: "Madrid has great players, they are experienced and will not be easily overcome.
"We were fortunate to win the last game but one day in the future we will lose to Real Madrid."
The Argentina midfielder also admits it would not be the end of the world if Barcelona were to lose in midweek.
He said: "It depends, because last year we lost in the cup and yet we continued with the league and Champions League and did well.
"It all depends on how you can respond later. Because it can affect you if you win, you can relax and not do well in the Champions League and league."
Barca have won their last seven successive competitive games at the Nou Camp, scoring a remarkable 35 goals and conceding none in the process, but they may not have it easy against a Betis side who look to be getting back on track after a dismal run of form.
Betis led the La Liga standings after winning their opening four games following promotion, but they then went into freefall, picking up just one point from their next 10 games.
However, the Andalusian club have now won four of their last five league and cup games - including triumphs over Valencia and Atletico Madrid - and full-back Jose Isidoro is hoping his side can continue that form against a Barca team he insists are not unbeatable.
"If you do a good job, take your chances and the team is on song, Barcelona are not invincible. The key is to score so they know we can hurt them," he said.
Like Barca, Betis also have a big game coming up the following week as they face bitter city rivals Sevilla in La Liga, but Isidoro says the derby remains on the backburner for now.
"The changing room is totally focussed on this game (against Barca). We are aware that any point we pick up is important towards staying up," he said.