Leicester Tigers returned to the top four in the Aviva Premiership and secured European Champions Cup qualification on Saturday but have been told they will need to improve with two games remaining in the league season.The 38-17 victory over bottom-of-the-table London Welsh came courtesy of tries from Laurence Pearce (2), Ben Youngs, Sam Harrison, Jamie Gibson and Tom Youngs as the visitors ended the game with 14 men following a 56th-minute red card for back-rower Chris Hala’Ufia.   A 13th league win of the season took Tigers above Exeter Chiefs and back into the top four with games against Wasps away and Northampton Saints at Welford Road to come.   “Welsh make sides work hard but in the end I think the scoreline is a fair reflection of the game,” said director of rugby Richard Cockerill.   “We were poor in the first half, we turned over ball and let them into the game. We showed good intent but we were far too inaccurate, turned over ball too easily and we looked a bit rusty. I challenged the players at half-time to make sure we did what we had worked on.   “The intent to play was right but if you don’t clear rucks and let the opposition on to the ball it is going to be hard, and they are tough to play against.   “We have to be a lot better for the next two games. We’re going to have a couple of hard weeks on the training field ironing out those issues.”   Tigers are at Wasps on Saturday, May 9 and then host Northampton Saints a week later. Match tickets for the Saints fixture have sold out, with only a limited number of hospitality places still available.