Abstract. The current tension in H_{0} measurements by Planck-2015 for $\Lambda$CDM and that by recent direct measurement by Riess et al. 2016, also results another tension in the value of r_{d}, the sound horizon at drag epoch, measured by BAO observations and Planck-2015. We show that, regardless of dark energy dynamics, to accommodate higher value of H_{0}, one needs a lower value of r_{d}, and so necessarily a modification of early universe cosmology. Later on, a model independent approach to constraint background evolution of the universe with low-redshift data, will be discussed.