Marcos Ayerza says the battle for a place in the Aviva Premiership top four is a great advert for English rugby.In one of the tightest play-off races in Premiership history, just three points separate second-placed Saracens and Exeter Chiefs in fifth place, with Wasps (6th) and Sale Sharks (7th) also in the hunt for a top-four finish.   Tigers are two places and two points behind Sarries heading into Saturday’s Round 19 fixture at Allianz Park (kick-off 3.15pm),   “It’s amazing how the Aviva Premiership has become so competitive this season,” said Ayerza, speaking at the launch of the Aviva Community Fund. “It can only be good for the sport, for the Aviva Premiership and for English rugby.   “It’s the business end of the season where every moment of every game is key. There are only four games left. The pressure is there for everyone to perform and be at their best.”   Tigers are on the back of a five-game winning run in the Aviva Premiership and, as well as Saturday's trip to Sarries, face Wasps away and London Welsh and Northampton Saints at home during the run-in.   Ayerza said: “We want to be in the play-offs, we want to be in the final, we want to be champions so to make that happen we have to beat the best sides around.   “It all starts in the run-in with these four games. It’s very exciting.”   Ayerza is supporting Hope Against Cancer during his testimonial year and backed the charity at the Aviva Community Fund launch, a nationwide initiative from Aviva, title sponsor of Aviva Premiership Rugby, which offers support and funding to causes close to your heart.   “The Aviva Community Fund would be vital to Hope Against Cancer and its work,” he said. “It is a cause that is close to my heart and I am really pleased to help.”   Visit aviva.co.uk/community-fund for more details on the Aviva Community Fund.