Roger Federer lost in three sets to 39-year-old Haas on making a return to the Tour after almost three months.
The Swiss 18-time Major champion wants to shed the 'practice world champion' tag and will be seen playing in Stuttgart this week.
The 18-time Grand Slam winner has won the French Open, contested on clay, just once in 2009, and also pulled out of the event last year with knee and back injuries.
The 18-time Grand Slam champion and the billionaire Microsoft co-founder will pair up in a one-set exhibition match in Seattle on April 29 to support children's education in Africa.
Roger Federer beat Rafael Nadal in straight sets 6-3, 6-4 to win his third Miami Open title.
Gear up for the mouth watering clash as Roger Federer will again battle it out for the summit clash against Rafael Nadal on Sunday.
Should Roger Federer win Friday, there is a chance he will play Sunday's final against long-standing rival Rafael Nadal, who faces Italy's Fabio Fognini in the other semi-final.
Rafael Nadal has never won the Miami Open despite being a four-time finalist and he expects plenty of work to get past Fabio Fognini and make it a fifth appearance.
Roger Federer is in fine form having clinched the Australian Open and Indian Wells so far this year and extended his record to 14-1.
Roger Federer couldn't help but laugh uncontrollably after listening to what his good friend Stan Wawrinks had to say to him after the match.
Federer beat Wawrinka in the final of Indian Wells on Sunday for his second win of the year following his triumph in the Australian Open - his 18th grand slam title and his first in four and a half years.
With Sunday's triumph in the all-Swiss final, Roger Federer joined Novak Djokovic as the only men to win five Indian Wells titles, adding to those he won in 2004, 2005, 2006 and 2012.
Swiss great Roger Federer will take on compatriot Stan Wawrinka in the Indian Wells Masters men's singles final on Sunday.
Roger Federer and other tennis stars had fun with the song 'Hard to Say I'm Sorry' by American rock group Chicago.
Federer, who added another chapter to a storied rivalry with Nadal with an epic Australian Open triumph in January, dismantled the Spaniard 6-2, 6-3 to advance.
The last time Nadal and Federer met before the quarter-finals of a tournament was their first meeting in the round of 32 at Miami in 2004.
Novak Djokovic launched his bid for a sixth ATP Indian Wells Masters crown with a two-set triumph over Kyle Edmund as the stars shone Sunday in the California desert.
Nick Kyrgios delivered another giant killer performance as he also beat Rafael Nadal and Roger Federer in their first ATP tour level meetings.