Brighton & Hove Albion goalkeeper Mathew Ryan (centre) and Tottenham Hotspur's Victor Wanyama battle for the ball during the Premier League match at Tottenham Hotspur Stadium (pic: John Walton/PA Images).
Speaking at a press conference ahead of the game, Pellegrini said: "Tottenham is a team that is doing a brilliant season".
West Ham are drifting in mid-table, 12 points clear of relegation and eight points off seventh place, and they have taken just a point in the four matches since they passed the 40-point mark.
Arsenal also have a two-legged Europa League semi-final against Valencia to come, with a possible final against Chelsea in Baku at the end of May, but Sokratis warned they can not afford to rely on winning the competition to qualify for next season's Champions League.
"We are in a position where it is now in our hands to be in the top four and if we are capable of winning the next three games in the Premier League for sure we will be third".
Son is enjoying a fantastic season and has stepped up to the plate for Spurs in Harry Kane's absence.
West Ham have fallen into an end of season slump. Furthermore, the Irons are the divisions lowest scorers away from home this calendar year.
Pellegrini says West Ham must improve on the number of goals they are conceding if they are to improve on what has been a "transition season" for the east London side.
"I'm a very positive guy, I'm very comfortable with the lads so I'll probably be more nervous watching in the stands than when I play". That point came last weekend when they held Leicester to a 2-2 draw.
Even in the event of a West Ham goal on Saturday, Spurs can be expected to continue their run of scoring in every game at their new home.
There was an evident lethargy in Pochettino's sides performance midweek, so the Hammers could give Spurs a scare.