Real Sociedad v Atletico Madrid: Siqueira talks up high spirits
The Liga champions are in superb touch and have won eight of their last nine in all competitions.
That form has lifted them to third in the table and just one point adrift of leaders and cross-town rivals Real Madrid.
Atletico's latest success was a 2-0 UEFA Champions League win at Malmo on Tuesday, a result that put them three points clear at the top of Group A.
Koke and Raul Garcia scored for Atletico in a professional road win and defender Guilherme Siqueira says the feel-good factor among the squad is high ahead of Sunday's clash.
"We keep growing during the matches," Siqueira told Atletico's official website.
"There has been much discussion about our set pieces, but in the last couple of matches we have been feeling good collectively, and when playing.
"The team keeps growing in all facets of the game and that's positive because we have footballers on this team to play attractive and beautiful games.
"We are following a good path and we must continue on it. The mentality of the coaching staff is seen through the players.
"This is what [coach Diego] Simeone preaches. We know what we play for and what we have to do on the field.
"Intensity is our keyword."
Just two points separate the top five in the Liga table, meaning victory - and other results going their way - could send Atletico top.
The departures of Diego Costa, Filipe Luis and Thibaut Courtois were expected to signal an end to Atletico's time at the top of the tree in Spanish football but Simeone's outfit look just as impressive this season.
But while Atletico could go top this weekend, Real Sociedad could drop to bottom - they sit 19th, just one point above the last-placed Cordoba.
Amazingly, Sociedad's only win this season came against European champions Real Madrid - who they beat 4-2 in August.
Strikers Carlos Vela, Imanol Agirretxe and Alfred Finnbogason have netted just three goals between them this term, though, and no Liga side has lost more games than the Basques.
That means Sociedad are rank outsiders to topple an Atletico side who are likely to be without Tiago and Cristian Ansaldi again.
Atletico won both clashes between the two sides last term, but Sociedad only have to look back to March last year for their last win against the champions of Spain.
Xabi Prieto scored the only goal in their 1-0 road win in March 2013.