They were in command at Clifton Lane last week, leading 13-0 in the second period before a woeful display saw them lose 31-30 in injury-time.
Richmond, promoted into the Championship this season, have lost all three games so far, conceding on average more than 40 points per fixture.
But Burnell said: “Despite them being new to the Championship we are expecting them to provide us with stiff competition, particularly as they are at home. They’ve probably looked at our performance against London Scottish and are feeling pretty confident.
“We were bitterly disappointed; we went in 10-0 up at the break and were looking good and in control.
“We came out for the second half added a penalty and we still looked comfortable.
“Then all of a sudden we start shipping points and they go on to score five tries. Apart from that being embarrassing, it’s a fact that some of our players were just too soft.”
Burnell has subsequently made changes to his side after two successive losses and added: “This week, the boys – as well as the coaching staff – have worked hard and we are all looking for a reaction.
“We fully expect them to give us a tough test.”