Brighton - who have reached the play-offs in the last two seasons - sit 22nd in the table after an awful run of form that has seen them win just one of their last 16 league matches.
Hyypia's position has come under scrutiny, with the former Liverpool defender - who was sacked by Bayer Leverkusen earlier this year - likely to need a quick turnaround to keep his job.
Brighton lost 3-0 at leaders Derby County last Saturday and now host a Millwall side just two points - and as many places - above them on the league table.
"Everyone knows it's a very important game," Hyypia is quoted as saying in The Argus.
"And, of course, for me personally, it's a very important game.
"I try to put it [criticism] to one side and concentrate on what I can control. I can't control people having their opinion.
"Whether it is going good or bad there are always critics and everyone has the right to give their opinion. I can't do anything about it."
Millwall have not beaten Brighton in their last six matches - a run dating back to January 2010.
At the other end of the table, Bournemouth take an 11-match unbeaten run into a home clash against Cardiff City.
Eddie Howe's men snapped a run of three successive draws with a 2-1 win at Wolverhampton Wanderers on Saturday and, led by the likes of Callum Wilson (nine goals), are the Championship's most prolific team, with 39 goals so far.
Derby have netted 38 and travel to fourth-placed Middlesbrough in another exciting match on Saturday.
Ipswich Town, who sit second, visit struggling Bolton Wanderers, while fifth-placed Brentford host a Blackburn Rovers side who are just two places below them.
Watford ended a four-match losing streak with a 5-0 demolition of Fulham last week and will be big favourites to defeat second-bottom Wigan Athletic, who have failed to improve under new manager Malky Mackay.
Fulham's next task comes at Elland Road, when Ross McCormack - the Championship's top scorer last term - returns to Leeds United.
Leeds sold McCormack for a reported £11million in the close-season as part of wholesale changes made by owner Massimo Cellino - recently disqualified from his position until March next year.
Italian Mirco Antenucci has tried to fill the void and has netted eight goals for Leeds this season, including four in his last four.
Rock-bottom Blackpool will go to Charlton Athletic in good spirits after just their second win of their season last week, while Rotherham United and Birmingham City - other sides in relegation danger - take on Nottingham Forest and Reading respectively.
Elsewhere, Norwich City take on Huddersfield Town and Sheffield Wednesday meet Wolverhampton Wanderers.
