WALTHAM - Al Horford impressed with CELTICS defense in NBA Preseason openerbr br br Follow @CLNSMedia on Twitterbr Subscribe to CLNS Media YouTube Channelbr Download the free CLNS Media Mobile APP for Android & iOSbr br Support our sponsor:br Hello Fresh! Go to www.HelloFresh.com and use promo code BEAT30 for THREE FREE meals & Free Shippingbr br A Production of CLNS Media Network.